APPLICATION OF PHOTOAFFINITY-LABELING WITH [11,12-H-3]ALL-TRANS-RETINOIC ACID TO CHARACTERIZATION OF RAT-LIVER MICROSOMAL UDP-GLUCURONOSYLTRANSFERASE(S) WITH ACTIVITY TOWARD RETINOIC ACID

[H-3]All-trans-retinoic acid has been shown to be an effective photoaf finity label for microsomal UDP-glucuronosyltransferases. Labeling of rat liver microsomal proteins with [H-3]all-trans-retinoic acid and [P -32]5-azido-UDP-glucuronic acid has shown that at least one protein in the 50-56 kDa mass range encompassing the UDP-glucuronosyltransferase s photoincorporated both probes. The fraction of solubilized microsoma l protein eluted from a UDP-hexanolamine affinity column with 50 mu M UDP-glucuronic acid contained two protein bands, both of which photoin corporated [H-3]all-trans-retinoic acid and were detected on Western b lot by anti-UDP-glucuronosyltransferase antibodies. Enzymatic glucuron idation activity toward at RA in the same fraction was enriched five-f old over that of native or solubilized microsomes. (C) 1997 Academic P ress.