title: A subclass of glutathione S-transferases as intracellular high-capacity and high-affinity steroid-binding proteins.
abstract: The distribution of glucocorticoids incubated with rat liver cytosol preparations or administered in vivo to adrenalectomized rats was analysed by chromatographic procedures. Corticosterone or dexamethasone was co-eluted with Yb-type GSH S-transferases in anion-exchange and gel-permeation chromatography systems, and these glucocorticoids also were bound to Yb forms in analyses by immunoadsorbent and lysyl-GSH affinity matrices. Pretreatment of cytosol with lysyl-GSH to extract GSH S-transferases or incubation with excess bilirubin, which is expected to compete with steroids for binding to the protein, yielded preparations that were devoid of this major steroid-binding component. In mixtures of the multiple rat GSH S-transferases, corticosterone preferentially interacted with Yb forms rather than Ya and Yc subgroups. All of the multiple Yb forms resolved by chromatofocusing procedures retained the steroid-binding capacity. It is suggested that these abundant proteins can account for a considerable share of intracellular glucocorticoid binding and represent a high-affinity non-saturable binding component with potential to function in steroid-hormone metabolism and action.
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D003345:Corticosterone / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D003907:Dexamethasone / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D011485:Protein Binding; D051381:Rats
chemical_list: D007527:Isoenzymes; D003907:Dexamethasone; D005982:Glutathione Transferase; D003345:Corticosterone