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18 Cards in this Set
- Front
- Back
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Ligand binding causes dissociation of:
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alpha and beta/gamma subunits
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What causes the alpha subunit of dissociate from the effector?
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GTP is hydrolyzed to GDP
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What must occur for a alpha subunit to interact with the effector?
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The ligand binds causing a conformational change, this releases the alpha subunit and allows it to bind GTP.
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Gs
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couples to adenylate cyclase
Stimulates AC activity Increases cAMP Activates PKA |
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Gi
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couples to adenylate cyclase
Inhibits AC activity decreases cAMP Inhibits PKA |
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Gq
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couples to phospholipase C
PIP2 cleaved to DAG IP3 Increase intercellular Ca activates PKC |
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Phospholipase C cleaves PIP2 into
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IP3 (hydrophillic) and DAG (hydrophobic)
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There are two types of guanylate cyclases, enzymes that make cGMP.
The one that is a cell surface receptor binds: The one that is in the cytosol binds: |
Atrial Natuiuretic Peptide
Nitric Oxide (soluble) |
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What is PKG?
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A cGMP dependent protein kinase, which phosphorylates proteins. This phosphorylation of proteins leads to the relaxation of smooth muscle.
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Explain the clinical significance of nitric oxide.
(given as nitroglycerin) |
Due to the fact that it is so soluble, it can readily be absorbed and can, via cGMP and protein kinase G, relax the smooth muscle cells surrounding the heart during angina. (chest pain due to lack of O2 to the heart, can preclude an MI)
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Once cAMP is generated, its signaling effects are short lived because it is destroyed by
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phosphodiesterase
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cAMP activates:
cGMP activates: |
PKA
PKG |
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True or False
Same receptor, same signaling pathway, produces different endpoints in different tissues |
True
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Adrenergic receptors bind endogenous ligands such as:
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Epinephrine and norepinephrins
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What are the steps in which cells respond to persistent stimulation by decreasing the number of receptors available to respond to drug.
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Desensitization (phosphorylation)
Internalization (endocytosis) Down Regulation (degradation, transcription) |
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How is the transmembrane guanylate cyclase receptor similar to tyrosine kinase receptors?
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They are both single transmembrane receptors.
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The whole point of cyclic GMP and AMP is to
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activate their respective protein kinases and phosphorylate proteins.
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How is nitric oxide formed by the body.
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It is formed in the endothelial cells by nitric oxide synthase.
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