title: Cyclic AMP-dependent protein phosphorylation in chemosensory neurons: identification of cyclic nucleotide-regulated phosphoproteins in olfactory cilia.
abstract: Chemosensory dendritic membranes (olfactory cilia) contain protein kinase activity that is stimulated by cyclic AMP and more efficiently by the nonhydrolyzable GTP analog guanosine-5'-O-(3-thio)triphosphate (GTP gamma S). In control nonsensory (respiratory) cilia, the cyclic AMP-dependent protein kinase is practically GTP gamma S-insensitive. GTP gamma S activation of the olfactory enzyme appears to be mediated by a stimulatory GTP-binding protein (G-protein) and adenylate cyclase previously shown to be enriched in the sensory membranes. Protein kinase C activity cannot be detected in the chemosensory cilia preparation under the conditions tested. Incubation of olfactory cilia with [gamma-32P]ATP leads to the incorporation of [32P]phosphate into many polypeptides, four of which undergo covalent modification in a cyclic nucleotide-dependent manner. The phosphorylation of one polypeptide, pp24, is strongly and specifically enhanced by cyclic AMP at concentrations lower than 1 microM. This phosphoprotein is not present in respiratory cilia, but is seen also in membranes prepared from olfactory neuroepithelium after cilia removal. Cyclic AMP-dependent protein kinase and phosphoprotein pp24 may be candidate components of the molecular machinery that transduces odor signals.
mesh_terms: D000818:Animals; D002923:Cilia / Q000201:enzymology*; D000242:Cyclic AMP / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology*; D009830:Olfactory Bulb / Q000166:cytology*; D010750:Phosphoproteins / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011895:Rana ridibunda; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D007527:Isoenzymes; D010750:Phosphoproteins; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C