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

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