Requirement for a reduced sulphydryl entity in the protection of molybdate-stabilized estrogen receptor.

The separate and combined effect of molybdate and dithiothreitol on the stability of human uterine 9 S estrogen receptor were studied. Maximal, short-term, protection of the 9 S estrogen receptor was achieved by the joint inclusion of both stabilizing agents in cytosol buffers. This molybdate--dithiothreitol-mediated stability was dependent on reducing agent concentration inferring sulphydryl involvement in 9 S receptor protection by molybdate. The study also showed that molybdate--dithiothreitol could not prevent the gradual decay of the 9 S estrogen receptor to the 4 S form in cytosols stored at 4 degrees C over prolonged periods.