IDENTIFICATION AND PURIFICATION OF CA2+ CALMODULIN-DEPENDENT PROTEIN-KINASE-V FROM HUMAN GASTRIC-CARCINOMA/

We previously purified a novel Ca2+/calmodulin-dependent protein kinas e (CaM kinase) V, which has proven to be a member of the CaM kinase I family. Immunohistochemical staining of surgically-resected specimens from human subjects using specific antibody which reacts with CaM kina ses I and V demonstrated heterogeneous distribution of CaM kinase I/V in normal gastric mucosa. The kinase was located mainly at the bottom of foveoral epithelium and in the gastric gland (< 25% immunopositive) . In contrast, this kinase was abundant in various types of gastric ca rcinomas (> 75%), but not in gastric adenomas. Preferential and consis tent presence of this kinase was confirmed by immunoblot analysis of g astric carcinoma and human gastric cancer cell lines, Kato-III and MKN -45. CaM kinase I/V was co-purified with CaM kinase II from resected g astric carcinoma using anion-exchange chromatography followed by calmo dulin-affinity chromatography. The two kinases were finally separated by HPLC-based gel filtration. Purified CaM kinase I/V from gastric car cinoma did not possess detectable autophosphorylating activity, in con trast to CaM kinase II. The findings suggest CaM kinase I/V may posses s abnormal biochemical properties in human gastric carcinoma, and the kinase could participate in cell growth of the carcinoma.