Studies in vitro of the effects of adenosine 3':5'-cyclic monophosphate on the phosphorylation of nuclear proteins in isolated rat heart nuclei.
Isolated rat heart nuclei were prepared by homogenization and sucrose-density-gradient centrifugation. The protein/DNA ratio of these nuclei was 3.1:1 (w/w), and the histones/non-histone proteins/DNA proportions were 1.4:1.6:1 (by wt.). Non-histone proteins were fractionated into six major groups by elution on a quaternized anion-exchanger (QAE-Sephadex A-50 column with increasing concentrations of NaCl in 5M-urea/0.01 M-Tris/HCl buffer (pH8.3). When isolated nuclei were incubated in a medium containing [gamma-32P]ATP, a differential distribution of 32P was observed in the six fractions of nonhistone proteins. The fractions eluted from the Sephadex column with 0.35M- and 0.6M-NaCl contained contained 80% of the total radioactivity incorporated into the non-histone proteins. This incorporation into the 0.35M- and 0.6M-NaCl fractions was increased by 66 and 112% respectively in the presence of cyclic AMP. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of these two particular fractions showed a selective increase in labelling of five protein bands in the presence of cyclic AMP.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology*; D004247:DNA / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D009206:Myocardium / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013268:Stimulation, Chemical
D011506:Proteins; D010758:Phosphorus; D000255:Adenosine Triphosphate; D004247:DNA; D000242:Cyclic AMP