EVIDENCE OF TRUE PROTEIN-KINASE CKII ACTIVITY IN MITOCHONDRIA AND ITSSPERMINE-MEDIATED TRANSLOCATION TO INNER MEMBRANE

A true protein kinase CKII (CKII) activity was characterized in liver mitochondria by its phosphorylating activity on the specific peptide s ubstrate of CKII, the binding and elution profile of the enzyme on a p hosphocellulose column and immunostaining of a 36 kDa polypeptide with antibodies against the cx-subunit of human CKII. This CKII activity w as located predominantly in the intermembrane space of quiescent mitoc hondria. A translocation of the enzyme to inner membrane of energized mitochondria occurred in the presence of spermine. Translocated CKII a ctivity was tightly bound to inner membrane, and high salt concentrati ons were necessary to release the activity. The inner face of the inne r membrane could constitute the in vivo localization of mitochondrial CW since the potential substrates of the enzyme are 4 matrix proteins.