title: Sec16 influences transitional ER sites by regulating rather than organizing COPII.
abstract: During the budding of coat protein complex II (COPII) vesicles from transitional endoplasmic reticulum (tER) sites, Sec16 has been proposed to play two distinct roles: negatively regulating COPII turnover and organizing COPII assembly at tER sites. We tested these ideas using the yeast Pichia pastoris. Redistribution of Sec16 to the cytosol accelerates tER dynamics, supporting a negative regulatory role for Sec16. To evaluate a possible COPII organization role, we dissected the functional regions of Sec16. The central conserved domain, which had been implicated in coordinating COPII assembly, is actually dispensable for normal tER structure. An upstream conserved region (UCR) localizes Sec16 to tER sites. The UCR binds COPII components, and removal of COPII from tER sites also removes Sec16, indicating that COPII recruits Sec16 rather than the other way around. We propose that Sec16 does not in fact organize COPII. Instead, regulation of COPII turnover can account for the influence of Sec16 on tER sites.
authors.affiliation: Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637 Department of Molecular Biology, Princeton University, Princeton, NJ 08544.
authors.forename: Nike
authors.initials: N
authors.lastname: Bharucha
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Effrosyni
authors.initials: E
authors.lastname: Papanikou
authors.forename: Conor
authors.initials: C
authors.lastname: McMahon
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Esaki
authors.forename: Philip D
authors.initials: PD
authors.lastname: Jeffrey
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Hughson
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Glick
mesh_terms: D001665:Binding Sites / Q000235:genetics; D022181:COP-Coated Vesicles / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D009154:Mutation; D010843:Pichia / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D005656:Fungal Proteins; D049452:Green Fluorescent Proteins