Phosphorylation of 2-5A core 5'-diphosphate to 2-5A in mouse L cell extracts.

When added to extracts of mouse L cells containing ATP and an energy regenerating system, the 5'-diphosphate of 2-5A core, pp5'A2'p5'A2'p5'A, as well as a bromoadenylate analog, pp5' (br8A)2'p5'(br8A)2'p5'(br8A), can be phosphorylated to the corresponding 5'-triphosphate, ppp5'A2'p5'A2'p5'A and ppp5'(br8A)2'p5'(br8A)2'p5(br8A), respectively. The extent of this conversion was about 0.5% when the concentration of 5'-diphosphate was about 10(-4) M. Thus, although previous studies have shown that the 5'diphosphate, pp5'A2'p5'A2'p5'A, can activate the 2-5A-dependent endonuclease, this may be related to a phosphorylation reaction in the crude cell extracts employed in these studies and may not represent a true ability of such a 5'-diphosphate to activate directly the endonuclease.