Cross-reaction of a plant protein kinase with antiserum raised against a sequence from bovine brain protein kinase C regulatory sub-unit.

The partly purified calcium-dependent, phospholipid-activated protein kinase from A. tricolor seedlings contains three major protein species (Mr = 84,500, 65,000 and 40,000) which cross-react with antiserum raised against the regulatory domain of bovine brain protein kinase C. Two of these species (Mr = 84,500 and 40,000) were phosphorylated when the preparation was incubated with [gamma-32P] ATP. It is suggested that the three cross-reacting proteins correspond to native enzyme, partly proteolysed enzyme and regulatory sub-unit respectively.