title: Protein phosphorylation in human peripheral blood lymphocytes. Subcellular distribution and partial characterization of adenosine 3':5'-cyclic monophosphate-dependent protein kinase.
abstract: Cytoplasmic and membrane fractions prepared from human peripheral-blood lymphocytes both contained cyclic AMP-dependent protein kinase activity and endogenous protein kinase substrates. Protein kinase activity in the particulate fractions was not eluted with 0.25 M-NaCl, suggesting that it was not derived from non-specifically absorbed soluble cytoplasmic protein kinase. Nor was the particulate protein kinase activity eluted by treatment with cyclic AMP, suggesting that the catalytic subunit is membrane-bound and arguing against cyclic AMP-induced translocation of particulate activity. Cyclic AMP-dependent protein-phosphorylating activity in the cytoplasmic fraction was highly sensitive to inhibition by Mn2+, and was co-eluted from DEAE-cellulose primarily with type-I rabbit skeletal-muscle kinase. Cyclic AMP-dependent phosphorylating activity in the plasma-membrane fractions was stimulated at low [Mn2+] and inhibited only at high [Mn2+]. When solubilized with Nonidet P-40, plasma-membrane protein kinase was co-eluted from DEAE-cellulose with type-II rabbit muscle kinase. These differences, together with the strong association of the particulate kinases with the particulate fraction, suggest the possibility of compartmentalized protein phosphorylation in intact lymphocytes.
mesh_terms: D002364:Caseins / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D000242:Cyclic AMP / Q000494:pharmacology; D003902:Detergents; D006657:Histones / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D008345:Manganese / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000097:blood*; D012995:Solubility; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D002364:Caseins; D003902:Detergents; D006657:Histones; D008345:Manganese; D000242:Cyclic AMP; D011494:Protein Kinases