Inhibition by acidic phospholipids of protein degradation by ER‐60 protease, a novel cysteine protease, of endoplasmic reticulum

Publisher Website
Google Scholar
Abstract
A protein (ER60) with sequence similarity to phosphoinositide-specific phospholipase C-α purified from rat liver endoplasmic reticulum (ER) degraded ER resident proteins and is really a protease [(1992) J. Biol. Chem. 265, 15152-15159]. Therefore, ER60 is called ER-60 protease. We now show that negatively charged phospholipids, phosphatidylinositol, phosphatidylinositol 4,5-bisphosphate and phosphatidylserine inhibit ER protein degradation by ER-60 protease. Phosphatidylcholine and phosphatidylethanolamine show no effect on the activity of ER-60 protease. With the use of protease inhibitors, ER-60 protease is shown to be a novel cysteine protease distinct from those of the cylosol and lysosomes.