Phosphorylation of low molecular mass cytosolic proteins by protein kinase C and protein kinase A in the rabbit exocrine pancreas.
Subcellular fractionation of rabbit pancreatic acini was performed to study the distribution of endogenous substrates for protein kinase C. Substrates for protein kinase C were found to be predominantly low molecular mass proteins of cytosolic origin. At least three of these soluble substrates, with molecular masses of 17-19 kDa, were relatively heavily phosphorylated by endogenous as well as purified pancreatic protein kinase C. In the same molecular mass range, 16-18 kDa, soluble proteins were also phosphorylated by protein kinase A. Moreover, addition of cyclic AMP under conditions that activated protein kinase C gave a more than additive labelling of these low molecular mass proteins. The latter observation may be of interest in view of the potentiating effect cyclic-AMP-activated protein kinase A has on amylase secretion stimulated by secretagogues which increase free cytosolic Ca2+ and activate protein kinase C.
Ederveen
A G
AG
Department of Biochemistry, University of Nijmegen, The Netherlands.
van der Leest
J V
JV
van Emst-de Vries
S E
SE
de Pont
J J
JJ
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002458:Cell Fractionation; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D010179:Pancreas / Q000201:enzymology* / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011817:Rabbits; D013379:Substrate Specificity
D011506:Proteins; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C; D002118:Calcium