Stabilization of thymic glucocorticoid-receptor complexes by the calcium-activated protease inhibitor, calpastatin.
We previously described a heat-stable factor from WEHI-7 mouse thymoma, rat liver, spleen, and human chronic lymphocytic leukemia cells that prevents degradation of glucocorticoid-receptor complexes (GRC) in cytosols from rat thymus and acute non-lymphocytic leukemia cells. We now show that the factor has many properties in common with calpastatin, a naturally occurring inhibitor of a family of neutral calcium-activated proteases called calpains. Liver GRC-stabilizing activity and calpastatin activity, in addition to surviving boiling, co-chromatography on columns of DEAE-cellulose ion exchange or agarose A-0.5M gel filtration matrices, and have identical isoelectric points of 5.1. This factor should be especially useful for studying GRC function in the presence of calcium.
D000315:Adrenalectomy; D000818:Animals; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002460:Cell Line; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D006801:Humans; D007525:Isoelectric Focusing; D008099:Liver / Q000032:analysis; D051379:Mice; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000494:pharmacology*; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013950:Thymus Gland / Q000187:drug effects / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D011480:Protease Inhibitors; D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; C033668:calpastatin