RAPID DEGRADATION OF NAD BY RETINOIC ACID-DIFFERENTIATED HL-60 GRANULOCYTE MEMBRANES PREVENTS ADP-RIBOSYLATION

Pertussis and cholera toxins failed to ADP-ribosylate Gα(s) and Gα(i) in membranes isolated from retinoic acid-differentiated HL-60 granulocytes, although Gα(i) subunits were present. NAD was rapidly degraded in the presence of these membranes, primarily to ADP-ribose, to less than 10% of initial activity by 5 min. Metabolism of NAD was heat labile and inhibited by NADP, but not by imidazole or isonicotinic acid hydrazine. Pertussis toxin uncoupled LTB4 receptors from G proteins in intact retinoic acid- differentiated HL-60 cells. Retinoic acid differentiation stimulates expression of a unique NAD-glycohydrolase activity in HL-60 granulocytes which prevents ADP-ribosylation in isolated membranes, but not intact cells. © 1993 Academic Press, Inc.