Lactacystin is a microbial metabolite isolated from Streptomyces that is now widely used as a selective inhibitor of the 20S proteasome.{10086,2351,10073} Clasto-lactacystin B-lactone was later identified as the active metabolite of lactacystin, resulting from the elimination of cysteine and the formation of a reactive B-lactone. Both lactacystin and its B-lactone metabolite induce differentiation and inhibit cell cycle progression in several tumor cell lines.{1659} Clasto-lactacystin B-lactone irreversibly alkylates subunit X of the 20S proteasome.{10073} 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 B-lactone are pleiotropic and depend substantially on the expression pattern of signaling proteins within the treated cell.
1 mg
CAS number
Cayman Chemical
Shipping & storage
Shipping condition
Dry Ice
Storage temperature