The macro-ER-phagy pathway and ERQC.

2015-07-16T02:50:24Z (GMT) by Zhanna Lipatova Nava Segev
<p><b>A.</b> Diagram illustrating three major ERQC pathways. Whereas native proteins are transported from the ER to through the Golgi for secretion (blue), three different pathways shuttle membrane and proteins for degradation by (green). ERAD shuttles misfolded proteins to the proteasome for degradation. Upon ER stress induced by tunicamycin or DTT, excess membrane is shuttled to the lysosome via micro-ER-phagy, which does not require neither Atgs nor Ypt GTPases. Here, macro-ER-phagy, which requires Atgs and Ypt GTPases, is shown to shuttle excess membrane proteins for degradation in the lysosome. <b>B.</b> Model of three discreet steps in macro-ER-phagy that carry ER-phagy cargo (e.g., overexpressed GFP-Snc1-PEM) to the lysosome for degradation: 1) Atg9-dependent formation of ER-to-autophagy membranes (ERAM) and induction of UPR; 2) Ypt1-dependent assembly of ERAM with PAS proteins (e.g, Atg1, Atg8 and Atg11); UPR is induced in mutant cells blocked in this step; 3) Vps21-dependent delivery of APs carrying ER-phagy cargo to the lysosome. See text for discussion.</p>