Insulin stimulates the generation of an adipocyte phosphoprotein that is isolated with a monoclonal antibody against the regulatory subunit of bovine heart cAMP-dependent protein kinase.
Incubating 32P-labeled fat cells with insulin increased by as much as 80-fold the amount of 32Pi in a soluble species of apparent Mr 62,000. This species, designated isp62, was specifically immunoprecipitated from cellular extracts with a monoclonal antibody against the type II regulatory subunit (RII) of cAMP-dependent protein kinase. Fat-cell RII, purified from extracts with cAMP-Sepharose or labeled with 8-azido [32P]cAMP, had an apparent Mr 51,000. Peptide mapping indicated that isp62 and adipocyte RII were different proteins. When cells were metabolically labeled with [35S]methionine, insulin stimulated the appearance of 35S-labeled isp62, indicating that the hormonal effect involves generation of the protein. The insulin-induced increase in isp62 could be observed within 1 min, occurred with physiological concentrations of the hormone, and was rapidly reversible. The increase in isp62 was unaffected by cycloheximide, indicating that insulin stimulates the posttranslational processing of a precursor, rather than de novo synthesis of the protein.
D000273:Adipose Tissue / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal; D002417:Cattle; D003429:Cross Reactions; D000939:Epitopes; D007328:Insulin / Q000494:pharmacology*; D008970:Molecular Weight; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000276:immunology / Q000378:metabolism; D011499:Protein Processing, Post-Translational
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007328:Insulin; D010750:Phosphoproteins; D011494:Protein Kinases