Effect of snap freezing, dithiothreitol and storage on estimations of estrogen receptor sites

Estrogen receptor assays were performed on human myometrium in order to determine optimal conditions for certain steps of the assay. The findings indicate that: (1) tissue should be snap-frozen in liquid nitrogen prior to assay, (2) dithiothreitol does not increase measurable binding site numbers, (3) estrogen receptors in the cytosol fraction are unstable and should be stored in excess of 1 day; (4) if storage prior to receptor assay is unavoidable, tissue should be stored at -20 degrees C or -70 degrees C for no longer than 1 week.