Mitochondrial and nuclear glucocorticoid-sensitive alkaline proteases in thymocytes

Glucocorticoid-sensitive alkaline proteases are localized in the nuclear and mitochondrial fractions of rat thymocytes. Dexamethasone load increased alkaline protease activity in the nuclear fraction and decreased or even eliminated it in the mitochondrial fraction. The inhibitory analysis showed that SH groups and disulfide bonds play a crucial role in the functioning of glucocorticoid-activated nuclear alkaline protease. Hence, this enzyme can be assigned to as cysteine proteases. Mitochondrial alkaline protease is a serine hydrolase, although it does not belong to the class of trypsin- or chymotrypsin-like enzymes. The role of alkaline proteases in apoptotic death of thymocytes is discussed.