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Definition
| An enzyme that converts ATP to cyclic AMP in response to an extracellular signal. |
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| A type of programmed cell death, which is brought about by activation of enzymes that break down many chemical components in the cell. |
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Definition
| Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells. It is also a regulator of some bacterial operons. |
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Definition
| A second messenger produced by the cleavage of the phospholipid PIP2 in the plasma membrane. |
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| A GTP-binding protein that relays signals from a plasma membrane signal receptor, known as a G protein-coupled receptor, to other signal transduction proteins inside the cell. |
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| G protein-coupled receptor (GPCR) |
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Definition
| A signal receptor protein in the plasma membrane that responds to the binding of a signaling molecule by activating a G protein. Also called a G protein-linked receptor. |
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Definition
| In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids and act on specific target cells in other parts of the body, changing the target cells’ functioning. Hormones are thus important in long-distance signaling. |
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Term
| inositol triphosphate (IP3) |
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Definition
| A second messenger that functions as an intermediate between certain signaling molecules and a subsequent second messenger, Ca2+, by causing a rise in cytoplasmic Ca2+ concentration. |
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Definition
| A molecule that binds specifically to another molecule, usually a larger one. |
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Definition
| A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions; also called an ionotropic receptor. |
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Definition
| A secreted molecule that influences cells near where it is secreted. |
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Definition
| An enzyme that transfers phosphate groups from ATP to a protein, phosphorylating the protein. |
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Definition
| An enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effect of a protein kinase. |
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Term
| receptor tyrosine kinases (RTKs) |
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Definition
| A receptor protein spanning the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein. Receptor tyrosine kinases often respond to the binding of a signaling molecule by dimerizing and then phosphorylating a tyrosine on the cytoplasmic portion of the other receptor in the dimer. The phosphorylated tyrosines on the receptors then activate other signal transduction proteins within the cell. |
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Definition
| A type of large relay protein to which several other relay proteins are simultaneously attached, increasing the efficiency of signal transduction. |
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Term
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Definition
| A small, non-protein, water-soluble molecule or ion, such a calcium (Ca2+) or cyclic AMP, that relays a signal to a cell’s interior in response to a signaling molecule bound by a signal receptor protein. |
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Term
| signal transduction pathway |
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Definition
| A series of steps linking a mechanical, chemical or electrical stimulus to a specific cellular response. |
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