11:115:301 Lecture Notes - Lecture 10: Creb, Adenylyl Cyclase, Protein Kinase A
22 Sep 2019
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Document Summary
Epinephrine secreted by the adrenal glands in response to internal + external stressors. Epinephrine signal ligand binding to protein (b-adrenergic receptor) B-ar is a member of the largest class of cell-surface receptors seven- transmembrane-helix (7tm) receptors. Responsible for transmitting information initiated by diverse signals: Rhodopsin - protein in retina of the eye senses the presence of photons + initiates signaling cascade responsible for visual sensation. Protein kinase a turned on by camp covalently modifies enzymes in the cell. Pka 2 regulatory + 2 catalytic chains (r2c2) Bind camp release catalytic chains catalytically active. Binds catalytic site with pseudosubstrate domain (rrgai) Bind camp r subunits dissociate with c subunits active. Phosphorylate proteins with the aa sequence rrgsi. Pka stimulates the expression of specific genes by phosphorylating a transcriptional activator called camp response element binding (creb protein) Signal-transduction pathways extend into the nucleus alter gene expression. G proteins reset themselves through gtp hydrolysis. Phosphoinositide cascade converts extracellular signals into intracellular ones.
