CALCIUM-DEPENDENT AND PHOSPHOLIPID-DEPENDENT PROTEIN-KINASE FROM BARLEY LEAVES - ISOLATION, CROSS-REACTIVITY, AND PROPERTIES

A preparation of calcium- and phospholipid-dependent protein kinase was isolated from barley (Hordeum vulgare L.) leaf cytosol by ion-exchange chromatography on DEAE-cellulose followed by affinity chromatography on adenine-linked Sepharose. The protein kinase revealed a cross-reactivity with monoclonal antibodies against the rat brain protein kinase C. Polypeptides from barley leaf cytosol and histone H1 were the substrates for the isolated protein kinase. Its activity was stimulated by 1,2-sn-diacylglycerol. With regard to its specificity for substrates and activators, the enzyme resembled C-type protein kinases. From barley leaf cytosol, a calcium- and phospholipid-independent protein kinase with a mol wt of 48 +/- 2 kD was also isolated. This enzyme might be a catalytically active fragment of C-type protein kinase.