Phosphorylation of casein, fibrinogen and calmodulin by a glycoprotein protein kinase from monkey cerebellum: a casein kinase II-like enzyme.

ABSTRACT

A glycoprotein protein kinase was isolated from monkey cerebellum by polylysine-Sepharose chromatography and affinity chromatography on Sepharose 4B coupled to the lectin, Concanavalin A. The protein kinase phosphorylated casein on serine and threonine residues and was stimulated by polylysine, polyarginine, spermine, histone, protamine and sphingosine, but was inhibited by heparin, poly (Glu, Ala, Tyr) and poly (Glu, Tyr). These characteristics were typical of casein kinase II. The protein kinase also phosphorylated fibrinogen and calmodulin and exhibited similar characteristics of stimulation by polylysine or polyarginine. The phosphorylation of fibrinogen (a glycoprotein), but not casein or calmodulin (non-glycoproteins), was significantly inhibited by Concanavalin A. Unlike casein kinase II, the enzyme did not undergo autophosphorylation. The collective results suggested that the enzyme from monkey cerebellum was a casein kinase II-like protein kinase and that phosphorylation of a glycoprotein substrate (fibrinogen) by the kinase could be influenced by a carbohydrate binding lectin.