DEMONSTRATION OF A DOUBLE-STRANDED DNA-STIMULATED PROTEIN-KINASE (DNA-PK) INHIBITORY ACTIVITY IN HUMAN HL-60 LEUKEMIA-CELLS

A 41,000 protein, p41, was highly purified from human promyelocytic HL -60 cells by chromatography on GTP-agarose columns. The purified p41 i nhibited phosphorylation of endogenous substrates present in partially purified DNA-PK from HL-60 or HeLa cells, as well as phosphorylation of recombinant protein tau mediated by the purified HeLa DNA-PX. The a bility of p41 to inhibit DNA-PK was largely abolished by heating at 95 degrees C for 30 min. (C) 1994 Academic Press, Inc.