IDENTIFICATION OF ENZYMATICALLY ACTIVE CA2+ CALMODULIN-DEPENDENT PROTEIN-KINASE IN CENTROSOMES OF HEMATOPOIETIC-CELLS/

In this study, we report the identification of enzymatically active, m ultifunctional calcium/calmodulin-dependent protein kinase in centroso mes of FDCP1 cells using subcellular fractionation and immunofluoresce nce techniques. Centrosomes were isolated from detergent lysates of FD CP cells by sucrose density gradient centrifugation and contain tubuli n (M(r) = 58 kDa) and centrin (M(r) = 20 kDa) by immunoblotting. Analy sis of these fractions with anti-calcium/calmodulin kinase II antibody revealed the presence of the 52 kDa and 56 kDa doublet corresponding to the alpha and the beta/beta subunits of the enzyme complex. In vitr o kinase reactions with isolated centrosomes and in the presence of ca lcium and calmodulin results in the phosphorylation of several centros omal proteins.