Protein kinase CKII: possible regulation by interaction with protein substrates.
Rat liver cytosolic CKII shows heterogeneity resulting from association of the alpha/alpha'-subunits with the beta-subunit or with a phosphorylatable protein of 49 kDa (pp49). Preparations of pp49 were resolved into several spots by two dimensional analysis which might be derived from different degrees of phosphorylation. pp49 was phosphorylated in vitro by purified rat liver CKII and to a lower extent by purified rat brain protein kinase C. In all cases, phosphorylation of pp49 occurred exclusively on Ser. Phosphopeptide maps of phosphorylated pp49 confirmed that the phosphorylation by CKII or PKC takes place in different sites. Prior phosphorylation of pp49 by protein kinase C had no significant influence on the increase of the Km value for beta-casein of CKII, caused by pp49. A tryptic peptide from pp49 has been recently sequenced and antibodies against it had been raised. The antibodies were able to recognize pp49 in rat liver extracts as well as in HL-60 extracts what leads us to presume that this kind of interaction might exist in other species and tissues.
Plana
M
M
Departament de Bioquímica i Biologia Molecular, Facultat de Ciències, Universitat Autònoma de Barcelona, Spain.
Gil
C
C
Molina
E
E
Itarte
E
E
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000201:enzymology; D047390:Casein Kinase II; D002364:Caseins / Q000378:metabolism; D002846:Chromatography, Affinity; D003600:Cytosol / Q000201:enzymology; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009928:Organ Specificity; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
D002364:Caseins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases