Article ID Journal Published Year Pages File Type
3030387 Thrombosis Research 2006 9 Pages PDF
Abstract
Endoglycosidase H digestion and immunofluorescence staining revealed the mutant being retained in the ER. Epoxomicin, a potent and specific proteasome inhibitor, and Ala-Ala-Phe-CH2Cl (AAF), an inhibitor of tripeptidyl peptidase II (TPPII), suppressed the intracellular degradation of the mutant by about 65% and 50%, respectively. When epoxomicin was combined with AAF, the inhibitory effect was substantially enhanced. Although castanospermine, an inhibitor of glucosidases I and II, did not affect the degradation, kifunensine, an inhibitor of ER mannosidase I, suppressed it. Thus, it appears that the Y595C mutant is degraded through more than one pathway of ERAD, including the proteasome-dependent pathway and an alternate proteasome-independent pathway where proteases such as TPPII may be involved. Production of the critical B isoform of Man8GlcNAc2 targets the mutant for ERAD, however, the interaction with calnexin/calreticulin through monoglucosylated oligosaccharides may not be required for the degradation of the mutant.
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