Term
| ALL TRIMERIC G-Proteins have this type of membrane receptor protein associated with them. |
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Definition
| 7-pass helix transmembrance domain receptor If trimeric G protein --> think 7 Pass! |
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Term
| Membrane receptors utilize .....soluble ligands |
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Definition
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Term
| second messengers often times do this |
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Definition
| Activate a Protein kinase |
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Term
| To modify the ACTIVITY of the protein, the protein is ........... |
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Definition
phosphorylated!
Note: Activity changes b/c 2 things happened (molecule has gained an extra negative charge AND/OR the molecule has changed conformation)
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Term
| After Phosphorylation, it takes (minutes, hours) for a response. Choose one |
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Definition
Minutes.
Note: Control of gene expression, however, takes hours Either by water soluble hormones (CREB protein) or by steroid (lipid soluble) hormones. |
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Term
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Definition
| Trimeric G protein that STIMULATES adenylate cyclase |
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Term
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Definition
Trimeric G protein that INHIBITS adenylate cyclase
Thus, less cAMP and therefore, less active PKA |
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Term
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Definition
| Trimeric G protein that STIMULATES phospholipase C |
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Term
| 2nd messengers for Gs and Gq pathways are? |
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Definition
Gs --> cAMP
Gq --> DAG (diacylglycerol), IP3 (inositol triphosphate), and Ca2+ |
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Term
| The amino acids to be phosphorylated in the PKA pathway are often ...(1)...and..(2)...because they contain nucleophilic...(3)...atoms that attack the electrophilic P of the phosphates. |
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Definition
1) Serines (Ser, S)
2) Threonine (Thr, T)
3) Oxygen |
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Term
| What amino acid is phosphorylated in the hormone pathway that involves a dimerization of two transmembrane proteins? |
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Definition
| Tyrosine residues have the nucleophilic Oxygens that can be phosphorylated. They undergo a transphosphorylation-autophosphorylation reaction. |
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Term
Write out simple pathway to STIMULATE Protein Kinase A (PKA)
---(+)---> means stimulates |
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Definition
Gs-Protein --(+)--> adenylate cyclase --> converts ATP to cAMP ---(+)--> active PKA
Called PKA b/c of the "A" in Adenylate cyclase |
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Term
Write out simple pathway to STIMULATE Protein Kinase C (PKC)
---(+)---> means stimulates |
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Definition
Gq-protein --(+)--> Phospholipase C --(+)--> breakdown of phospholipids into 2nd messengers (DAG and IP3).
IP3 -(+)-> Ca2+ release from ER to cytosol
DAG + Ca2+ --(+)--> PKC
Called PKC b/c of the "C" in Ca2+ |
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Term
| Trimeric vs. Monomeric G proteins |
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Definition
Trimeric:
1) Alpha, Beta and Gamma subunits
2) Cell Surface receptor signals
Monomeric
1) Receptor linked (like Ras)
2) Vesicle sorting/fusion (Rab)
3) Actin cytoskeleton (Rac, Rho) |
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Term
| How does a cell 'know' that a receptor tyrosine kinase has been activated? |
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Definition
| When the SH2 protein (Src Homology 2 protein) binds to PHOSPHORYLATED Tyr residues, the SH2 changes conformation and this signals the cell. |
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Term
| What is one signal resulting from an SH2-SH3 adaptor proteins phosphotyrosine binding? |
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Definition
| One result may be the eventual stimulation of the MONOMERIC G Protein (p21-ras) encoded by the ras gene, which leads to the MAP (Mitogen Activating Protein) Kinase cascade and leads to increased Mitosis --> more cell division. If uncontrolled, tumors may grow. |
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Term
| Why is a phosphorylation cascade prevalent in cell signaling pathways? |
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Definition
| It allows for an AMPLIFICATION of the signal and increased regulatory sites in the pathway. |
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Term
| Which type of receptor would the epidermal growth factor most likely be associated with? |
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Definition
| Tyrosine Kinase Receptor b/c many growth factor pathways (cell division and/or cell differentiation) are prevalent. |
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Term
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Definition
GAP = GTPase Activating Protein
makes GTP --> GDP. Ex. INACTIVATES ras (monomeric G protein)
GEF = GTP Exchange Factor
Put GTP on ras protein and GDP drops off (ACTIVATES ras) |
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Term
*NOT TESTED in Unit 4*
Phosphorylating gene regulatory proteins (ie CREB) controls gene expression. CREB induces PEPCK gene. The increase in in number of PEPCK would (increase,decrease,not affect) the Km and (increase,decrease,not affect) the Vmax |
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Definition
not affect Km b/c structure of PEPCK is not changed (no affinity change)
Increase in Vmax b/c the gene has been amplified (more of it present and active) |
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