Common non-hormone binding component in non-transformed chick oviduct receptors of four steroid hormones

Abstract

Steroid hormones produce a response in target cells by binding to hormone-specific soluble receptors, which undergo a transformational change, leading to their interaction with chromatin and to modified gene expression. In a previous paper, we described a monoclonal antibody, BF4, that specifically recognizes and binds the non-transformed '8S' form of chicken oviduct progesterone receptor (8S-PR). We now show that BF4 does not form an immune complex with the 4S transformed form of 3H-progestin-labelled progesterone receptor, but does interact with the 8S non-transformed forms of the oestrogen, androgen and glucocorticosteroid receptors. Our results suggest that the antigenic determinant recognized by BF4 is present on a non-hormone binding unit, which we identify as a polypeptide of molecular weight (MW) 90,000 in the case of the progesterone receptor, and that this unit is common to other 8S non-transformed chicken steroid receptors.

Chick oviduct glucocorticosteroid receptor

“…The function of this 90-kDa antigen is not yet understood. Moreover, recent studies have shown that the molybdate-stabilized 8-S forms of the estrogen and androgen receptors from chick oviduct cytosol, as well, interact with BF4 monoclonal antibody [16]. However, when gradient ultracentrifugation was performed in the presence of 0.5 M KCl, all steroid hormone receptors sedimented at z 4 S, irrespective of the presence of BF4 monoclonal antibody.…”

Purification and characterization of an endogenous inhibitor specific to the Z‐Leu‐Leu‐Leu‐MCA degrading activity in proteasome and its identification as heat‐shock protein 90

“…It is one of the most abundant cellular proteins found even under nonstress conditions. It has been found to be associated with a number of other intracellular proteins, including actin [28,29], pp60"-"', pp140fp", ~~94~"" [30,31], and steroid hormone receptors [32]. It is suggested that HSP90 plays several important roles in cells, one being to act as a chaperon.…”

Firefly luciferase mutants as sensors of proteome stress

“…Later, Hsp90 was found to be associated with several different clients such as protein kinases and nuclear steroid receptors (e.g. glucocorticoid receptor) (Joab et al, 1984;Schuh et al, 1985;Smith, 1993;Smith et al, 1992). Since then, Hsp90 clients have grown tremendously owing to genome-wide high throughput studies.…”