Exam Review - Chapter 12

Occupied receptor causes gdp gtp exchange on gq 3 gq

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Unformatted text preview: sidue for Phosphorylation How to turn off activity: 1. System becomes desensitized as epinephrine concentration falls below the Kd 2. Hydrolysis of GTP bound to the Gα, catalyzed by the intrinsic GTPase 3. Remove cAMP by hydrolysis through cyclic nucleotide phosphodiesterase 4. Phosphatase removes the phosphate, hydrolyzes Ser, Thr, or Tyr residues Desensitization occurs after epinephrine binds to the receptor 1. Gsβγ recruits βARK to the membrane, where it phosphorylates Ser residues on carboxyl terminus 2. Recruits β- arrestin to the phosphorylated carboxyl- terminal domain receptor 3. Receptor- arrestin enters cell by endocytosis 4. In cell, arrestin dissociates; receptor is dephosphorylated and returned to cell cAMP acts as a secondary messenger for many regulatory molecules Some hormones (somastostatin) operate by inhibiting adenylyl cyclase through the activation of inhibitory G protein, or Gi AKAPs: multivalent adaptor proteins, one part binds to the R subunits of PKA and another to...
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