A calmodulin dependent protein kinase in parietal cells.
An enriched population of isolated rabbit gastric parietal cells, from the fundic mucosa of New Zealand White rabbit, contained an active cytosolic calmodulin-dependent protein kinase activity with a prominent 100 kDa substrate (pp100). The latter focused as a doublet with isoelectric point of 6.8-7.0. The pp100 protein was phosphorylated only on threonine residues on a single tryptic peptide. Trifluoperazine inhibited the pp100 kinase activity with a KI of 10-15 microM. Addition of exogenous calmodulin was able to restore activity to uninhibited levels. A protein band with a molecular weight and phosphopeptide map identical to pp100, phosphorylated by calcium-dependent kinase, was also observed in rabbit pancreatic cytosol. The data suggest that a type III calmodulin-dependent kinase is present in parietal cell cytosol.
Department of Surgery, West Haven Veterans Administration Medical Center, New Haven, Connecticut 06520.
M
M
Oddsdottir
I M
IM
Modlin
K A
KA
Zucker
M J
MJ
Zdon
J R
JR
Goldenring
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology*; D003600:Cytosol / Q000201:enzymology; D008970:Molecular Weight; D010179:Pancreas / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D013270:Stomach / Q000201:enzymology*
D002147:Calmodulin; D010750:Phosphoproteins; D010769:Phosphothreonine; D011494:Protein Kinases; D002118:Calcium