PHOTOAFFINITY-LABELING OF ANDROGEN RECEPTORS WITH 17-BETA-HYDROXY-17ALPHA-[H-3]METHYL-4,9,11-ESTRATRIEN-3-ONE

The synthetic androgen 17.beta.-hydroxy-17.alpha.-[3H]methyl-4,9,11-estratrien-3-one (R1881 [methyltrienolone]) was used as a photoaffinity label to characterize androgen receptors in calf uterus and rat prostate. Polyacrylamide gel electrophoresis, under denaturing conditions, showed that the DNA-binding form of the androgen receptor in calf uterus cytosol is a protein with a molecular mass of 98 kD [kilodalton]. In rat prostate cytosol, an androgen receptor with a molecular mass of 46 kD could be photoaffinity labeled with R1881. The photoaffinity labeling procedure described here provides a method for studying the hormone binding domain of androgen receptors in partial purified preparations.