Cell Biology of the Endoplasmic Reticulum and the Golgi Apparatus through Proteomics

Squaring the EMC – how promoting membrane protein biogenesis impacts cellular functions and organismal homeostasis

“…Bioinformatic analysis of subunit topologies predicted significant mass on either side of the ER membrane, connected by membrane-spanning domains in seven out of ten subunits. At a 1:1 stoichiometry, the EMC is anticipated to contain at least 12 TMDs (Goytain and Quamme, 2008;Richard et al, 2013;Ring et al, 2008;Smirle et al, 2013). EMC1, EMC7 and EMC10 were predicted to contain signal sequences and adopt a type-I transmembrane protein topology (Junes-Gill et al, 2011;Ninagawa et al, 2015), which was confirmed by the detection of N-linked glycans on both EMC1 and EMC10 (Chen et al, 2009;Junes-Gill et al, 2011;Ninagawa et al, 2015).…”

Mammalian ER mannosidase I resides in quality control vesicles, where it encounters its glycoprotein substrates

“…A proteomics study of rat liver ( Gilchrist et al. , 2006 ), reevaluated later ( Smirle et al. , 2013 ), identified most of ERManI in a vesicular fraction containing COPI vesicles, which might have included other, then-uncharacterized, vesicles as well (QCVs).…”

N‐Glycan‐based ER Molecular Chaperone and Protein Quality Control System: The Calnexin Binding Cycle

“…At first glance, the ER is separated into two morphologically distinct regions: the perinuclear rough-ER decorated with ribosomes; and the smooth ER that lacks ribosomes but extends throughout most mammalian cells to create a number of functional regions. The lectin chaperones are dispersed throughout both distinct areas (98,99). Calnexin and calreticulin have also been found in locations outside the ER, suggestive of them playing roles beyond the confines of the ER boundaries (100).…”