Steroid receptor folding by heat-shock proteins and composition of the receptor heterocomplex.

Over the past 2 years, reports from several laboratories have supported the proposal that the steroid receptors are bound through the hormone-binding domain to a protein complex that contains three heat-shock proteins-hsp90, hsp70, and hsp56. This receptor-heat-shock-protein heterocomplex accounts for the behavior of the classic 9 S, non-DNA-binding form of the adrenocorticoid, sex hormone, and dioxin receptors. The receptor heterocomplex has now been reconstituted by an enzymatic system in reticulocyte lysate. This represents the first in vitro system for reversing receptor transformation, and this ability to reconstitute the receptor heterocomplex promises rapid advances in our understanding of how these receptors are folded, transported, and regulated by hormone in the cell.