Factors essential for desensitization of pigeon erythrocyte adenylate cyclase responsiveness in a cell-free system.
Cell-free desensitization of the pigeon erythrocyte adenylate cyclase-coupled beta-adrenoreceptor system requires soluble cellular factors. Desensitization is observed when a mixture of cell membranes and the cytosol fraction are incubated with isoproterenol or cAMP and IBMX for 20 min at 37 degrees C. Mg2+ and ATP are also required for cell-free desensitization. When adenylate cyclase is maximally stimulated by isoproterenol or GTP-gamma-S, the decrement of activity is 45-50% and 20-25%, respectively. Adenylate cyclase desensitization may be also produced by preincubation of plasma membranes with the catalytic component of cAMP-dependent protein kinase. Cell-free desensitization is associated with functional uncoupling of the beta-receptor. This is evidenced by an impaired ability of receptors to form a high affinity, guanine nucleotide-sensitive complex with the agonist and by the increase of the lag-phase of adenylate cyclase activation by isoproterenol and GTP-gamma-S. These findings suggest that one possible mechanism for the development of desensitization in adenylate cyclase systems may be the phosphorylation of a component(s) of the beta-receptor-adenylate cyclase complex which results in impaired receptor-cyclase coupling.
Popov
K M
KM
Bulargina
T V
TV
Severin
E S
ES
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000097:blood*; D000818:Animals; D001667:Binding, Competitive; D002474:Cell-Free System; D010856:Columbidae / Q000097:blood*; D000242:Cyclic AMP / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D004361:Drug Tolerance; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D011494:Protein Kinases / Q000097:blood; D013873:Thionucleotides / Q000494:pharmacology
D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D015056:1-Methyl-3-isobutylxanthine