Vitamin B6 and glucocorticoid action.

Abstract

THE MECHANISMS by which steroid hormones interact with target tissues to induce endocrine responses have been studied since the early 1960's (for a recent review see Ref. 1), and many contributions have added to our current understanding of steroid hormone action. In essence, it is believed that the lipophilic steroid hormones enter target tissues by passively diffusing across the cell membrane. Once inside the cell, steroids bind reversibly to cytosolic receptor proteins in a stereospecific fashion to form steroid-receptor complexes. The actual localization of these receptors in the cytoplasm of target cells is a controversial subject (2); however, for the purposes of this discussion, it will be assumed that these receptors are available for steroid binding in the cytoplasmic compartment of the cell. This complex then undergoes a physicochemical transformation, termed activation, which enables the complex to bind tightly to appropriate chromatin acceptor sites. The phenomenon of steroid receptor activati...