Binding of [³H]-4,5-Secodihydrotestosterone by Androgen Receptor¹)

Summary

Specific binding of [5,6-³H₂]-17ß-hydroxy-4,5-secoandrostan-3-one (or [³H]-4,5-secodihydrotestosterone, IX) to rat prostate cytosol receptors was observed and confirmed by two independent methods: by adsorption to dextran-charcoal and by polyacrylamide gel electrophoresis. The electrophoresis of [³H]-4,5-secodihydrotestosterone — cytosol mixtures showed a single radioactivity peak at different radioligand concentrations, displaceable by nonradioactive 4,5-secodihydrotestosterone ; the mobility of the peak corresponds to a protein with a relative molecular weight of 90000—130000. The apparent association constant of the compound with respect to adsorption to dextran-charcoal is 1.48xl0⁹l. mol⁻¹, similar to the value observed with dihydrotestosterone (4.8xl0⁸l.mol⁻¹).

Key Words

Antiandrogenic activity - Androgen receptor