Protein kinases and their protein substrates in free messenger ribonucleoprotein particles and polysomes from mouse plasmacytoma cells.
In free messenger ribonucleoprotein particles (mRNP) and polysomes from plasmacytoma cells, a phosphorylated protein/protein kinase system has been characterized by a combination of oligo(dT)-cellulose chromatography and CsCl isopycnic gradient centrifugation. The presence phosphorylated in vivo has been detected in both types of particles. Endogenous protein phosphorylation occurs in vitro by particle-associated cAMP-independent protein kinase(s) using [gamma-32P]ATP and [gamma-32P]GTP. These kinases are sensitive to hemin action. Analysis of mRNP proteins by gel electrophoresis and autoradiography showed strong analogies between the phosphorylation patterns obtained in vivo and in vitro, suggesting a substrate specificity for the associated enzymes. The phosphorylated proteins have been compared to initiation factors and ribosomal proteins. We have partially purified the cAMP-independent protein kinase activities responsible for the endogenous phosphorylation in free mRNP and polysomes; two activities were identified in free mRNP whereas three activities were found to be associated with polysomes.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D006160:Guanosine Triphosphate / Q000378:metabolism; D051379:Mice; D009374:Neoplasms, Experimental / Q000201:enzymology; D009698:Nucleoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010954:Plasmacytoma / Q000201:enzymology*; D011132:Polyribosomes / Q000201:enzymology*; D011494:Protein Kinases / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D013379:Substrate Specificity
D009698:Nucleoproteins; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D011494:Protein Kinases