title: Purification and characterization of hormone-regulated isoforms of the regulatory subunit of type II cAMP-dependent protein kinase from rat ovaries.
abstract: The regulatory subunit (R-II) of cAMP-dependent protein kinase type II is induced in rat ovarian granulosa cells by the synergistic actions of estradiol and follicle-stimulating hormone. The R-II from rat ovaries was compared with R-II from rat heart, rat brain, bovine heart, and bovine brain using immunological methods, 8-N3[32P]cAMP photoaffinity labeling and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Three isoforms of R-II were identified in rat ovarian cell extract (R-II54 Mr = 54,000, R-II52 Mr = 52,000, R-II51 Mr = 51,000), two isoforms of R-II in rat brain cell extract (Mr = 54,000, Mr = 52,000), and one isoform of R-II in rat heart cell extract (Mr = 54,000). Rat ovarian R-II54, heart R-II, and brain R-II (Mr = 54,000) were recognized by antiserum against rat heart R-II, whereas rat ovarian R-II52/R-II51 and rat brain R-II (Mr = 52,000) were not. In contrast, an antiserum raised against bovine heart R-II recognized all three isoforms of ovarian R-II as well as the lower molecular weight form of rat brain R-II. Ovarian types R-II52 and R-II51 but not R-II54 were increased selectively in granulosa cells by estradiol and follicle-stimulating hormone. In addition: 1) ovarian R-II52/51 subunits were purified to homogeneity and shown to recombine with C subunit from bovine heart to form a cAMP-dependent protein kinase; 2) pure R-II52/51 were not interconvertible to a higher molecular weight form by C subunit-dependent phosphorylation; 3) pure rat heart R-II (Mr = 54,000) and ovarian R-II52/51 exhibited distinct differences based on one- and two-dimensional peptide mapping; and 4) by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis pure R-II52/51 were resolved as three (rather than two) isoelectric variants which were clearly different from pure rat heart R-II54. Thus, the hormone-regulated form of R-II in rat ovarian granulosa cells appears to represent a gene product distinct from R-II54 in rat heart.
mesh_terms: D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D004357:Drug Synergism; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000201:enzymology; D007016:Hypophysectomy; D007163:Immunosorbent Techniques; D007527:Isoenzymes / Q000302:isolation & purification*; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology; D010053:Ovary / Q000201:enzymology*; D011494:Protein Kinases / Q000302:isolation & purification*; D051381:Rats
chemical_list: D000345:Affinity Labels; D007527:Isoenzymes; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D011494:Protein Kinases