A Calcium/Calmodulin-Binding Serine/Threonine Protein Kinase Homologous to the Mammalian Type II Calcium/Calmodulin-Dependent Protein Kinase Is Expressed in Plant Cells

Abstract

cDNA fragments corresponding to an apple (Malus domestica [L.] Borkh) calmodulin-binding polypeptide have been isolated and characterized. The protein encoded by this messenger contains a serine/threonine protein kinase catalytic domain followed by a calcium/calmodulin-binding regulatory domain, both exhibiting significant sequence similarities to the corresponding regions of the mammalian calcium/calmodulin-dependent protein kinase II subunits. These results confirm a potential regulatory role for calmodulin in phosphorylation-mediated signal transduction events.