Methyltrienolone, a specific ligand for cellular androgen receptors.

Methyltrienolone (R 1881), 17beta-hydroxy-17alpha-methyl-estra-4,9,11-trien-3-one, a very active androgen, binds specifically to rat prostate cytosol with a higher affinity than androstanolone. Unlike the physiological hormone, however, it is not bound by human sex steroid plasma binding protein, SBP. This specific ligand is thus a useful tool for the detection of elusive androgen receptors and for their study, for instance, in human tumors where interference from plasma contamination has to be circumvented.