Identification of a very large nuclear estrogen receptor complex

A high mol wt estrogen receptor complex (mol wt: > 669,000) has been isolated from chromatin prepared from mouse uteri with the use of multiple protease inhibitors, exposure to DNAase I, and size exclusion HPLC (SEHPLC). This complex is stable in the presence of molybdate and 0.4 M KC1. Because receptors in the cytosol do not. elute similarly to this large complex when investigated under a wide variety of conditions, it is unlikeiy that random receptor aggregation is responsible for the formation of this nuclear complex. Consequently, this complex may represent a collection of chromatin components that participate in the mechanisms of hormonal regulation. Since the large nuclear receptor complex can be isolated, this hypothesis can be readily subjected to extensive investigation.