Tosyl-lysyl chloromethane alters glucocorticoid-receptor complex nuclear binding and physical properties

We have investigated the effect of tosyl-lysyl chloromethane (a serine proteinase inhibitor) on rat liver cytosolic glucocorticoid-receptor complex binding to isolated nuclei. Tosyl-lysyl chloromethane (1-2 mM) significantly blocked nuclear binding when added before (but not after) thermal activation. Fifty percent inhibition occurred at about 1 mM tosyl-lysyl chloromethane. Interestingly, several other serine proteinase inhibitors (tosyl-phenylalanyl chloromethane, phenylmethyl sulphonylfluoride, and diisopropyl fluorophosphate) also depressed glucocorticoid-receptor complex nuclear binding. Tosyl-lysyl chloromethane, like molybdate, inhibited dilution-induced nuclear binding at low temperature, altered the DEAE-cellulose binding characteristics of heat-treated glucocorticoid-receptor complexes, and caused glucocorticoid-receptor complexes to sediment at about 9-10S (control complexes sedimented at 7-8S) in low salt-sucrose density gradients. Overall, these results suggest that tosyl-lysyl chloromethane modulates several properties of the glucocorticoid-receptor complex, that tosyl-lysyl chloromethane effects resemble those of molybdate, and that a serine proteinase(s) could be involved in the mechanism of glucocorticoid-receptor complex activation into a nuclear binding form.