Two novel effectors of trafficking and maturation of the yeast plasma membrane H+ ‐ATPase

ABSTRACT
The endoplasmic reticulum (ER) is the entry site of proteins into the endomembrane system. Proteins exit the ER via COPII vesicles in a selective manner, mediated either by direct interaction with the COPII coat or aided by cargo receptors. Despite the fundamental role of such receptors in protein sorting, only a few have been identified. To further define the machinery that packages secretory cargo and targets proteins from the ER to Golgi membranes, we used multiple systematic approaches, which revealed two uncharacterized proteins that mediate the trafficking and maturation of Pma1, the essential yeast plasma membrane proton ATPase. Ydl121c (Exp1) is an ER protein that binds Pma1, is packaged into COPII vesicles, and whose deletion causes ER retention of Pma1. Ykl077w (Psg1) physically interacts with Exp1 and can be found in the Golgi and COPI vesicles but does not directly bind Pma1. Loss of Psg1 causes enhanced degradation of Pma1 in the vacuole. Our findings suggest that Exp1 is a Pma1 cargo receptor and that Psg1 aids Pma1 maturation in the Golgi or affects its retrieval. More generally our work demonstrates the utility of high content screens in the identification of novel trafficking components.

Synopsis
Ydl121c (Exp1) and Ykl077w (Psg1) are two uncharacterized yeast proteins that mediate the trafficking and maturation of Pma1, the essential plasma‐membrane proton ATPase. Exp1 is an ER protein that is packaged into COPII‐vesicles, and whose deletion cau...

Source: Traffic - July 20, 2017 Category: Research Authors: Yosef Geva, Jonathan Crissman, Eric C. Arakel, Natalia G ómez‐Navarro, Silvia G. Chuartzman, Kyle R. Stahmer, Blanche Schwappach, Elizabeth A. Miller, Maya Schuldiner Tags: ORIGINAL ARTICLE Source Type: research