The common 90-kd protein component of non-transformed '8S' steroid receptors is a heat-shock protein

EMBO J. 1985 Dec 1;4(12):3131-5.


Non-transformed steroid receptors have an approximately 8S sedimentation coefficient that corresponds to an oligomeric structure of 250-300 kd which includes a non-hormone binding 90-kd protein. A monoclonal antibody BF4 raised against the purified, molybdate-stabilized, 8S progesterone receptor (8S-PR) from chick oviduct, recognizes 8S forms of all steroid hormone receptors. BF4 was found specific for a 90-kd protein present in great abundance in all chicken tissues, including that present in 8S-forms of steroid receptors. Here, using immunological and biochemical techniques, we demonstrate that this ubiquitous BF4-positive 90-kd protein is in fact the chicken 90 kd heat-shock protein (hsp 90): it increased in heat-shocked chick embryo fibroblasts, and displayed identical migration in two-dimensional gel electrophoresis and the same V8 peptide map as the already described hsp 90. We discuss the possibility that the interaction between hsp 90 and steroid hormone-binding subunits may play a role in keeping the receptor in an inactive form.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Chickens
  • Chromatography, Affinity
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes / analysis
  • Female
  • Heat-Shock Proteins / analysis*
  • Macromolecular Substances
  • Molecular Weight
  • Oviducts / metabolism
  • Receptors, Progesterone / analysis*


  • Antibodies, Monoclonal
  • Epitopes
  • Heat-Shock Proteins
  • Macromolecular Substances
  • Receptors, Progesterone