Lactacystin is a microbial metabolite isolated from Streptomyces which is now widely used as a selective inhibitor of the 20S proteasome. Clasto-lactacystin .beta.-lactone was later identified as the active metabolite of lactacystin， resulting from the elimination of cysteine and the formation of a reactive .beta.-lactone. Both lactacystin and its .beta.-lactone metabolite induce differentiation and inhibit cell cycle progression in several tumor cell lines. Clasto-lactacystin .beta.-lactone irreversibly alkylates subunit X of the 20S proteasome. It is at least 10 times more active than the parent compound； this increased activity may be a function of increased cell permeability. Inhibition of proteasome peptidase activity results in the accumulation of a variety of ubiquitinated proteins which would normally undergo rapid degradation. Thus， the effects of clasto-lactacystin .beta.-lactone are pleiotropic and depend substantially on the expression pattern of signalling proteins within the treated cell.
产品描述
Active metabolite of lactacystin， a widely used selective inhibitor of the 20S proteasome， with at least 10 times better activity； irreversibly alkylates subunit X of the 20S proteasome
