A novel protein kinase activity in rabbit gastric gland cytosol.
A novel protein kinase activity was characterized from the cytosolic fraction of isolated rabbit gastric glands. The kinase phosphorylated a major 33,000 Da endogenous protein (pp33) and was stimulated by Zn2+ and Mn2+ with Kact of 1.0 and 7.5 mM, respectively. Mg2+ and Ca2+ failed to stimulate any pp33 kinase activity. The kinase utilized both ATP and GTP as phosphate donors with a Km of 10 microM for both. The pp33 protein displayed an isoelectric point of 7.5 to 7.8 and was phosphorylated predominantly on threonine residues. The kinase activity is clearly differentiable from all reported kinase activities and appeared to be enriched in rabbit gastric fundic mucosa. The results indicate that gastric fundic mucosa contains a novel protein kinase activity.
D000818:Animals; D003600:Cytosol / Q000201:enzymology*; D005753:Gastric Mucosa / Q000201:enzymology*; D066298:In Vitro Techniques; D007525:Isoelectric Focusing; D008345:Manganese / Q000494:pharmacology; D010449:Peptide Mapping; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000032:analysis; D011817:Rabbits; D015032:Zinc / Q000494:pharmacology
D008345:Manganese; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D015032:Zinc