Term
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Definition
| Signaling molecules are often classified based on the __ between their site of production and the target tissue(s) upon which they act. |
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Term
| endocrine signals, circulatory |
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Definition
| Some messengers, such as hormones, act as __ __. THey are produced at great distances from their tartet tissues and are carried by the __ system to various sites in the body. |
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Term
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Definition
| Signals such as growth factors, are released locally, where they diffuse to act at short range on nearby tissues. Such signals are referred to as __ __. |
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Term
| juxtacrine signals, autocrine signals |
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Definition
| When signals are passed at such short range that they require physical contact between the sending and receiving cells, they are said to be __ __. Still other local mediators act on the same cell that produces them; such signals are called __ __. |
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Term
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Definition
| Once a messenger reaches its target tissue, it binds to __ on the surface on the target cells, initiating the signaling process. |
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Term
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Definition
| A molecule coming from either a long or a sort distance functions as a __ by binding to a receptor. A __ often binds to a receptor embeded within gthe plasma membrane of the cell receiving the signal. In other case, such as steroid hormones, the __ binds to a receptor inside the cell. In either case, the __ is a "primary-messenger." |
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Term
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Definition
| The binding of lignad receptor often results in the production of additional molecules within the cell receiving the signal. Such __ __ are small molecules or ions that relay the signals from one location of rhe cell, such as the plasma membrane, to the interior of the cell, intiating a cascade of damages within the receiving cell. Often these events affect the expression of specific genes within the receiving cell. |
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Term
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Definition
| The ultimate result is a change in the identity or function of cell. The ability of a cell to translate a receptor-ligand interaction to changes in its behavior or gene expresion is known as __ __. |
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Term
| peptides, fatty acids, nucleosides, nucleotides, bind |
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Definition
| Messenger molecules can be chemically characterized as amino acids or their derivatives, __, proteins, __ __, lipids __, or __. Many messengers are hydrophilic compounds whose function lies entirely in their ability to __ to one or more specific receptors on a target cell. |
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Term
| steroid hormones, retinoids |
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Definition
| Hydrophobic messengers, on the other hand, act on receptors in the nucleus or cytosol whose function is to regulate the transcription of particular genes. Among the hydrophobic messengers that bind to intrecellular receptors are __ __. Which are derived from the compound colesterol, and __ derived from vitamin A. |
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Term
| multiple, same, different, affects |
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Definition
| Different ways in which signals can be integrated: 1: One receptor activates __ pathways. 2: Different receptors activate the __ pathway. 3: Different receptors activate __ pathwyas; one pathway __ the other. |
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Term
| multiple, same, different, regulate |
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Definition
| Another way of wording the last flashcard. 1: One signal can activate __ signal transduction pathways. 2: Multiple signals can result in activation of the __ pathway. 3: Different signals can activate __ pathways, but one component of a pathway can __ a component of another pathway. |
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Term
| noncovalent (ionic), noncovalent |
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Definition
| A messenger forms __ ( __ ) chemical bonds with the receptor protein. Individual __ bonds are generally weak; therefore, several bonds must form to achieve strong binding. |
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Term
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Definition
| For a receptor to make numerous bonds with its ligand, the receptor must have a __ __that fits the messenger molecule closely, like a hand in a glove. |
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Term
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Definition
| Withing the ligand-binding site on the __, appropriate amino acid side chains must be positioned so that they can form __ __ with the messenger molecule. This combination of binding site shape and the strategic positioning of amino acid side chains within the binding site is what enables the receptor to distinguish its specific ligand from thousands of other chemicals. |
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Term
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Definition
| In most cases, the binding reaction between a ligand and the receptor specific for it, known as its __ __, is similiar to the binding of an enzyme to its substrate. |
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Term
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Definition
| When a receptor binds its ligand, the receptor is said to be __. Similarily, the ligand can be either __ (to a receptor) or __ in solution. |
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Term
| occupied, occupied, saturation, no |
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Definition
| The amound of receptor that is occupied by ligand is proportional to the concentration of free ligand in solution. As the ligand concentration increases, more and more of its cognate receptors become __, until most receptors are __-- a condition known as __. Further increases in ligand concentration will, in principle, have __ further effect on the target cell. |
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Term
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Definition
| The relationship between the concentration of ligand in solution and the number of receptors occupied can be described qualitatively in terms of __ __. |
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Term
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Definition
| When almost all of the receptors are occupied at low concentrations of free ligand, we way that the receptor has a __ affinity for its ligand. |
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Term
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Definition
| When it takes a relatively high concentration of ligand for most receptors to be occupied, we say that the receptor has a __ affinity for its ligand. |
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Term
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Definition
| Receptor affinity can be described quantitatively in terms of the __ __, kd, the concentration of free ligand needed to produce a state in which half the receptors are occupied. Values for kd range from roughly 10-7-10-10M. The importance of the value is that it tells us at what concentration a particular ligand will be effective in producing a __ __. |
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Term
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Definition
| Receptors with a high affinity for their ligands have a very __ dissociation constant. |
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Term
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Definition
| Receptors with a low affinity have a __ dissociation constant. |
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Term
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Definition
| Typically, the ligand concentration must be in the range of the kd value of the __ for the ligand to affect the target tissue. |
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Term
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Definition
| In addition to the intrinsic properties of the receptor, receptor-ligand interactions can also be affected by __ on the cell surface. |
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Term
| receptor, ligand, regulation |
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Definition
| Coreceptors help to facilitate the interaction of the __ with its __ through their physical interaction with the receptor. One well-studied class of such molecules are heparan sulfate proteoglycans, including glypicans and syndecans. Coreceptors provide another layer of __ of receptor-ligand interaction. |
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Term
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Definition
| Although receptors have a characteristic affinity for their ligands, cells are geared to sense __ in ligand concentration rather than fixed ligand concentrations. |
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Term
| adapts, increased, receptor down-regulation |
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Definition
| When a ligand is present and receptors are occupied for prolonged periods of time, the cell __ so that in no longer responds to the ligand. To further stimulate the cell, the ligand concentration must be __. Such changes are known as __ __-__. |
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Term
| density, receptor-mediated endocytosis, diminished |
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Definition
| 2 Main Ways: 1st: cells can change the __ of receptors on their surfaces in response to a signal. The removal or receptors from the cell surface takes place through the process of __-__ __, in which small portions of the plasma membrane containing receptors invaginate and are internalized. The reduced number of receptors on the cell surface result in a __ cellular response to ligand. |
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Term
| desensitization, lower, permanent, phosphate |
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Definition
| 2 Main Ways: 2nd way cells can adapt is known as __, which involves alterations of the receptor that __ its affinity for ligand or render it unable to initiate changes in cellular function. This provides a way for cells to adapt to __ differences in levels of messenger concentration. One common way this occurs involves addition of __ groups to specific amino acids within the cytosolic portion of the receptor. |
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Term
| synthetic ligands, receptor |
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Definition
| Although receptors have binding sites that fit the messenger molecule quite closely, it is possible to make similiar __ __ that bind even more tightly or selectively. This is especially important when more than one type of __ exists for the same ligand. |
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Term
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Definition
| Drugs that activate the receptor to which they bind are known as __. |
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Term
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Definition
| Normal messengers cause a change in the receptor when they bind, both synthetic and natural compounds have been discovered that bind receptors without triggering such a change. These __ inhibit the receptor by preventing the naturally occuring messenger from binding and activating the receptor. |
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Term
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Definition
| The G protein-linked receptor family is so named because ligand binding causes a change in receptor conformation that activates a particular __ __. |
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Term
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Definition
| A portion of the activated G protein in turn binds to a __ __, such as an enzyme or a channel protein, therby altering the target's activity. Examples of G protein-linked receptors include: olfactory receptors (smell), norepinephrine, hormone, follicle-sitmulating hormone receptors, also opioid receptors which narcotics bind to. These drugs also induce long-term changes in synaptic fuction in the brain that are responsible for their additive effects. |
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Term
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Definition
| G protein-linked receptors are remarkable in that they all have similar structure yet differ significantly in their __ __ sequences. |
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Term
| 7, extracellular fluid, cytosol |
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Definition
| In each case, the receptor protein forms __ transmembrane alpha helices connected by alternating cytosolic or extracellular loops. the N-terminus of the protein is exposed to the __ __, while the C-terminus resides in the __. |
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Term
| messenger-binding site, receptor |
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Definition
| The extracellular portion of each G protein-linked receptor has a unique __-__ __, and the cytosolic loops allow the __ to interact with only certain types of G proteins. |
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Term
| phosphorylation, desensitized |
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Definition
| G protein-linked receptors can be regulated in several ways. One of the most important way is by __ of specific amino acids in their cytosolic domain. When these amino acids are phosphorylated, the receptor becomes __. |
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Term
| G Protein-linked receptor kinase (GRKs) |
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Definition
| One class of proteins that carry out this function are __ __-__ __ __ ( __ ), which specifically act on activated receptors. |
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Term
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Definition
| When specific amino acids within the cytosolic portion of G protein-linked receptors, such as the beta-adrenergic receptor, are heavily phosphorylated by GRKs, a protein known as beta-arrestin can bind to them and completely __ their abilty to associate with G proteins. |
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Term
| protein kinase A (PKA), receptor, negative feedback |
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Definition
| Another kinase, __ __ __ ( __ ), which is itself activated by G protein-mediated signaling, can phosphorylate other amino acids on the __. Such inhibitory action is a good example of __ __ during cell signaling. |
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Term
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Definition
| G proteins act very much like molecular switches, whose "on" or "off" state depends on whether the G protein is bound to __ or __. |
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Term
| large heterotrimeric, Heterotrimeric |
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Definition
| There are two distinct classes of G proteins: the __ __ G proteins, contian three different subunits called G alpha, G beta, and G gamma. __ G proteins mediate signal transduction through G protein-linked receptors. The small monomeric G proteins include Ras. |
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Term
|
Definition
| G proteins have the same basic structure and mode of activation. Of the 3 subunits in the Gαβγ heterotrimer, Gα, the largest, binds to a __ nucleotide (GDP or GTP). When this binding occurs, it also __ from the Gβγ complex. The Gβ and Gγ subuints, on the other hand are permanetly __ together. |
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Term
|
Definition
| Some G proteins, such as Gs, act as __ of signal transduction; others, such as Gi, act to __ signal transduction. |
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Term
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Definition
| When a messenger binds to a G protein-linked receptor on the surface of the cell, the change in conformation of the receptor couses a G protein to associate with the receptor, which in turn causes the Gα subunit to release its bound __. |
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Term
|
Definition
| The Gα then acquires a new, different molecule of GTP and __ from the complex. Depending on the G protein and the cell type, either the free GTP-Gα subunit or the Gβγ complex can then __ signal transduction events in the cell. |
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Term
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Definition
| Each portion of the G protein exerts its effect by __ to a particular enzyme or another protein in the cell. In some cases, both the GTP-Gα and Gβγ subunits simulataneously regulate different processes in the __. |
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Term
| bound, hydrolyzes, shut down |
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Definition
The activity of a G protein persists only as long as the Gα subunit is __ to GTP, and the Gα and Gβγ subunits remain separated. Because the Gα subunit catalyzes GTP hydrolysis, it remains active only until it __ its associated GTP to GDP, at which time it reassociates with Gβγ. This feature allows the signal transduction pathway to __ __ when the messenger is utilized.
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Term
| regulators of G protein signaling, GTPase activating proteins |
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Definition
| Some Gα proteins are very ineffeceint at catalyzing GTP hydrolysis; however, their efficiency is dramatically improved by __ __ __ __ __ (RGS) proteins. When RGS proteins bind Gα, they stimulate GTP hydrolysis. Such __ __ __ (GAPs) are important regulators of G protein function, like Ras. |
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Term
|
Definition
| The large number of different G proteins provides for a diversity of G protein-mediated signal transduction events. Perhaps the most important is the release or formation of __ __. |
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Term
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Definition
| Two widely used second messengers are __ __ and __ ions, which stimulate the activity of target enzymes when their cytosolic concentrations are elevated. |
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Term
|
Definition
| A subunit is part of what protein structure? |
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Term
| Adenylyl cyclase, cytosol,Gs |
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Definition
| Cyclic AMP (cAMP) is formed from cytosolic ATP by the enzyme __ __, which is a enzyme that is anchored in the plasma membrane with its catalytic protion protruding into the __. Normally this enzyme is inactive until it binds to an activated Gα subunit of a specific G protein, such at __. |
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Term
|
Definition
| When a G protein-linked receptor is coupled to a Gs, the binding of ligand __ the Gsα subunit to release GDP and acquire a GTP. This in turn causes GTP-Gsα to __ from the Gsβγ subunits and bind to adenylyl cyclase. |
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Term
|
Definition
| When GTP-Gsα binds to adenylyl cyclase, the enzyme becomes __ and converts ATP to __. |
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Term
|
Definition
| Another Gα protein, Giα, __ adenylyl cyclase. |
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Term
|
Definition
| G proteins respond quickly to changes in ligand concentration because they remain active for only a __ time before the Gα subunit __ its bound GTP and converts to the inactive state. |
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Term
| cAMP, cAMP, phosphodiesterase, cAMP, declines |
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Definition
| Once the G protein becomes inactive, the adenylyl cyclase ceases to make __. However, __ levels would still remain elevated in the cell if not for the enzyme __, which degrades __. This further ensures that the signal transduction pathway will shut down promptly when the concentration of the ligand outside the cell __. |
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Term
| glycogen, contractions, contractions |
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Definition
| cAMP is important for many cellular events, a few such as: breaking down __ in the liver and skeletal muscles, increasing __ in cardiac muscles, and inhibit __ in smooth muscles. |
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Term
| protein kinase A, phosphate, serine, threonine, catalytic, catalytic |
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Definition
| cAMP appears to have one main intracellular target -- the enzyme __ __ __. PKA phoshphorylates a wide variety of cellular proteins by transferring a __ from ATP to a __ or __ found within the target protein. cAMP regulates the activity of PKA by causing the detachment of its two regulatory subunits from its two __ subunits. Once the __ subunits are free, PKA can catalyze the phosphorylation of various proteins in the cell. |
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Term
| absence, production, phosphodiesterase |
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Definition
| These cellular responses can be triggered even in the __ of a ligand. This can be done in 2 ways. 1st: by stimulating cAMP __ directly. 2nd: By inhibiting the enzyme __that degrades cAMP. |
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Term
| second messenger, uncommon, phospholipase C |
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Definition
| Inositol-1,4,5-triphosphate (IP3), one of the breakdown products of inositol phospholipids, functions as a __ __. IP3 is generated from phosphatidylinositol-4,5-biphosphate (PIP2), a realitively __ membrane phospholipid, when the enzyme __ __ is activated. |
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Term
|
Definition
| Phospholipase C cleaves PIP2 into two molecules-- __ and __ which are both second messengers in a variety of regulated cell functions. |
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Term
|
Definition
| A receptor is activated by the binding of its __. The receptor-ligand comples associates with the G protein Gq, causing displacement of GDP by GTP and __ of the α and βγ subunits |
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Term
| phospholipase C, PIP2, IP3, DAG |
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Definition
| The GTP-Gα complex then binds to __ __ activating it and causing cleavage of __ into __ and __ |
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Term
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Definition
| IP3 is released into the __ where it triggers __ release. |
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Term
| membrane, protein kinase C |
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Definition
| DAG remains in the __ where it activates __ __ __ |
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Term
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Definition
| Protein kinase C (PKC) is a family of enzymes that can phosphorylate specific __ and __ groups on a variety of target proteins. |
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Term
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Definition
| Ca+ ions play an essential role in regulating a variety of cellular functions. The concentration of Ca+ is normally maintained at very __ levels in the cytosol due tothe presence of __ __ in the plasma membrane and the ER. |
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Term
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Definition
| Calcium ATPases in the plasma membrane transport Ca+ __ of the cell, whereas the calcium ATPases in the ER sequester calcium ions in the __ of the ER. |
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Term
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Definition
| Some cells have sodium-calcium exchangers that further __ the cytosolic calcium concentration. |
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Term
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Definition
| Mitochondria can transport calcium into the __ __. |
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Term
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Definition
| For most cells in their __ state, the action of calcium ATPases maintaines the calcium concentration in the cytosol at 0.1μM. |
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Term
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Definition
| One way that a stimuli can cause cytosolic calcium concentrations to increase is in relation to neurons by the __ of calcium channels in the plasma membrane. Because the Ca+ concentration is so low inside the cell and so large outside the cell, when this channel opens, calcium ions __ into the cell. |
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Term
| intracellular stores, sarcoplasmic reticulum |
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Definition
| Calcium levels can also be elevated by the release of calcium from __ __. Calcium ions sequestered in the ER can be released through IP3 receptor channel. This is particularly important from the __ __ of cardiac and skeletal muscles, but nonmuscle cells such as neurons also have ryanodine receptors |
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Term
|
Definition
| Local calcium levels can affect a wide variety of cellular processes. One important process regulated by Ca+ is __, we saw that a neurotransmitter is a good example of calcium-regulated __. |
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Term
| calcium-mediated signal transduction, activation |
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Definition
| Fertilization of animal eggs is another striking example of the importance of __-__ __ __. In many animals, the release of Ca+ from inside the sperm cells results in their __. |
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Term
| egg, fertilization, internal stores, penetrates |
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Definition
| Activated sperm can then bind to the surface of mature __ and unite with them at __, triggering a striking sequence of events. One of the early responses of the egg--within 30 seconds to several min after fertilization -- is the release of Ca+ from __ __. Calcium release occurs initially at the site where the sperm __ the egg surface and then spreads across the egg by calcium-induced calcium release. |
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Term
| cortical granules, unable, slow block to polyspermy |
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Definition
| The calcium release is necessary for 2 crucial events. First, the exocytosis of vesicles known as __ __, which results in alterations of the protein coat surrounding many eggs. These alterations render the egg __ to bind to additional sperm, therby preventing more than one sperm from fertilizing the egg. This process is known as the __ __ __ __. |
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Term
|
Definition
| The second major function of the calcium wave following fertilization is __ __, which involves the resumption of many metabolic processes, the reorganization of the internal contents of the egg, and other events that initiate the process of embryonic deveolpment. |
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Term
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Definition
| Many features of the slow block to polyspermy and egg activation can be initiated by treating unfertilized eggs with __ __ in the absence of __, demonstrating the key role elevated calcium levels within the egg play in its activation. |
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Term
|
Definition
| Egg activation is a good example of how dynamic change in Ca+ concentration can result in __ cellular response. |
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Term
|
Definition
| The Gβγ subunit can also engage in signaling. For ex. G protein receptor kinase, which we have already encountered, can be activated by the βγ subunit of a dissociated G protein, providing a __ __ of G protein signaling. |
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Term
|
Definition
| When acetylcholine binds to the __ acetylcholine receptor, the βγ subunit of its associated G protein acts on potassium channels in the plasma membrane, causing them to open. When acetylcholine is no longer present, the α and βγ subunits __, causing the potassium channels to close agian |
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Term
| interior, signal transduction |
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Definition
| G protein-linked receptors transmit their signals to the __ of the cell by causing changes in a G protein, which in turn initiates a cascade of __ __ events. |
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Term
| receptors, protein kinases, stimulated |
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Definition
| Protein kinase-associated receptors not only function as __, but are themselves __ __. When they bind to the appropriate ligand, their kinase activity is __, and they transmit signals through a cascade of phosphorylation events within the cell. |
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Term
| phosphate, phosphorylate, tyrosine, phosphorylate, serine, threonine |
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Definition
| kinases add a __ group to particular amino acids within substrate proteins. Major kinds are those that __ a __ residue, and those that __ a __ or __ residue. |
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Term
| cell proliferation, nutrients, signals |
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Definition
| Protein Kinase-associated receptors come into play in __ __. For a cell to divide, it must have all the __ needed for synthesis of its component parts, but the availability of nutrients in usually not itself sufficient for growth. Cells often need additional __ to stimulate cell growth. |
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Term
|
Definition
| Serum was able to support the growth of cells, wheras __ would not. Many of the messengers present within the serum have now been purified, and they are now members of various classes of proteins known as __ __. |
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Term
|
Definition
| Plasma is a whole blood, including unreacted __ but without the red and white blood cells. Serum is the clear fluid remaining after blood has __. |
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Term
| fibroblasts, connective tissue |
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Definition
| During clotting, platelets secrete growth factors into the blood that stimulate the growth of cells called __, which form the new __ __ that makes up a scar. After clotting, the resulting serum is full of platelet-derived growth factor (PDGF). Plasma does not contain this factor because clotting has not taken place yet. |
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Term
| tyrosine kinase, tyrosine kinase |
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Definition
| The receptor for PDGF is a receptor __ __. In fact, several growth factors act by stimulating receptor __ __. |
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Term
|
Definition
| Growth factors are secreted molecules that act at __ __ and have specific effects on cells possessing the appropriate __ to sense the presence of the growth factor. |
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Term
|
Definition
| Many receptor tyrosine kinases (RTKs) trigger a chain of __ __ events inside the cell that ultimately lead to cell growth, proliferation, or the specialization of cells. |
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Term
| insulin, nerve, epidermal |
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Definition
| Examples of RTKs include: the __ receptor, the __ growth factor receptor, and the growth factor (EGF) receptor. |
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Term
| structurally, polypeptide chain |
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Definition
| Receptor tyrosine kinases differ __ from G protein-linked receptors in many ways. These receptors often consist of a single __ __ with only one transmembrane segment. |
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Term
| ligand-binding domain, tyrosine kinase, tyrosine |
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Definition
| Within this polypeptide chain are several distinct domains. The extracellular portion of the receptor conatins the __-__ __. The other end of the peptide protrudes through the plasma membrane into the cytosol. On the cytosolic side, a portion of the receptor forms the __ __. The cytosolic portion of the receptor contains __ residues that are in fact themselves targets for the tyrosine kinase portion of the receptor. |
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Term
| nonreceptor tyrosine kinase |
|
Definition
| The tyrosine kinase is a frequent integral part of the receptor protein. In some cases, hoewver, the receptor and the tyrosine kinase are two separate proteins, and the tyrosine kinase is then referred to as a __ __ __. However, it can bind to the receptor and be activated when the receptor binds its ligand. |
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Term
|
Definition
| Signal transduction is initiated when a __ __, causing the receptor tyrosine kinases to aggregate. In many of the best understood cases, __ receptor molecules cluster together within the plasma membrane when they bind ligand. |
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Term
| phosphorylates, autophosphorylation |
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Definition
| Once the receptor cluster in this wa, the tyrosine kinase associated with each receptor __ the tyrosines of neighboring receptors of the same type, this process is referred to as __. |
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Term
|
Definition
| Once autophosphorylation of tyrosine residues on the cytosolic portion of the receptor occurs in response to __ __, the receptor recruits a number of cytosolic proteins to interact with itself. Each of these proteins binds to the receptor at a phosphorylated tyrosine residue. |
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Term
| phosphotyrosine, SH2 domain |
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Definition
| To bind to the receptor, each cytosolic protein must contain a stretch of amino acids that recognizes the __ and a few neighboring amino acids on the receptor. The portion of the protein that recognizes one of these phosphorylated tyrosines is called and __ __. |
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Term
| different, several, activates |
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Definition
| Recruitment of different SH2 domain-containing proteins activates __ signal transduction pathways. As a result, receptor tyrosine kinases can activate __ different signal transduction pathways at the same time. These include: inositol-phospholipid-calcium second messenger pathway, and the Ras pathway, which ultimately __ the expression of genes involved in growth or development. |
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Term
|
Definition
| Ras is important in regulating the growth of cells. It comprises a single subunit. Ras and other __ __ G proteins are important signaling molecules. |
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Term
|
Definition
| Ras can either be bound to GDP or GTP, but is only active when it is bound to __. __ is a GEF (guanine-nucleotide exchange factor) that can activate Ras in the absence of a receptor __. |
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Term
|
Definition
| For Sos to become active, it must bind __ to the receptor tyrosine kinase through another protein called __, which contains an SH2 domain. |
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Term
|
Definition
| Thus, to activate Ras, the receptor becomes tyrosine phosphorylated, and GRB2 and Sos form a complex that binds to the receptor, __ Sos. Sos then __ Ras to release GDP and acquire GTP, which converts Ras to its active state. |
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Term
|
Definition
| Once Ras is active, it triggers a series of __ reactions. The first protein in this cascade is a protein kinase called __. |
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Term
|
Definition
| Activated Raf phosphorylates serine and threonine residues in a protein kinase known as MEK. MEK can then phosphorylate threonine and tyrosine residues in a class of proteins known as __. |
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Term
| transcription factors, Jun, Ets |
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Definition
| One functon of MAPKs is to phosphorylate nuclear proteins, known as __ __, that regulate gene expression. Two nuclear proteins are __ and __. |
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Term
| hydrolysis, GTPase activating protein |
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Definition
| Once Ras is in its active state, it must be inactivated by __ of the GTP bound to it to avoid continued stimulation of the Ras pathway. GTP hydrolysis is facilitated by a __ __ __, GAPs can accelerate inactivation of Ras a hundredfold. |
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Term
|
Definition
| Receptor tyrosine kinases, like G protein-linked receptors can also activate phospholipase C which leads to the production of __ (which releases calcium from intracellular stores) and __. |
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Term
|
Definition
| Cγ (activated by receptor tyrosine kinases) is different from Cβ (activated by the G protein-linked receptors) in that it contains an __ __ and must bind to the receptor. Once it binds to the receptor, phospholipase Cγ is phosphorylated by the receptor tyrosine kinase and becomes active. |
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Term
|
Definition
| Receptor tyrosine kinase can activate other enzymes, such as phosphantidylinositol 3-kinase (PI 3-kinase), which phosphorylates the plasma membrane phospholipid phosphatidylinositol, which is important for regulating __ __ and __. |
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|
Term
| transforming growth factor β (TGFβ) |
|
Definition
| Another major class of protein kinase-associated receptors uses a very different set of signal transduction pathways to elicit changes within the cell. These receptors phosphorylate serine and threonine residues rather they tyrosine. One major class of serine-threonine kinase receptors comprises a family of proteins that bind membres of the __ __ __ _ ( __ ) family of growth factors. |
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Term
| clusterd, phosphorylated, cytosol |
|
Definition
| In the absence of TGFβ, the type I and type II receptors for TGFβ are not __ or __. R-Smads and Smad4 are in the __. |
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Term
| clustering, type I, type II |
|
Definition
| Binding of TGFβ results in __ of type I and type II receptors, followed by phosphorylation of __ _ by __ _ |
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|
Term
| anchoring protein, R-Smad |
|
Definition
| The activated type I receptors bind a complex of an __ __ and a _-__, resulting in R-Smad phosphorylation. |
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Term
| nucleus, gene expression, degraded, cytosol |
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Definition
| The phosphorylated R-Smad binds Smad4, and the complex enters the __. Along with other proteins, they activate or repress __ __. Eventually, the R-Smad is __ or leaves the nucleus, and Smad4 returns to the __, terminating the signal. |
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