title: Coordination of golgin tethering and SNARE assembly: GM130 binds syntaxin 5 in a p115-regulated manner.
abstract: During membrane traffic, transport carriers are first tethered to the target membrane prior to undergoing fusion. Mechanisms exist to connect tethering with fusion, but in most cases, the details remain poorly understood. GM130 is a member of the golgin family of coiled-coil proteins tat is involved in membrane tethering at the endoplasmic reticulum (ER) to Golgi intermediate compartment and cis-Golgi. Here, we demonstrate that GM130 interacts with syntaxin 5, a t-SNARE also localized to the early secretory pathway. Binding to syntaxin 5 is specific, direct, and mediated by the membrane-proximal region of GM130. Interestingly, interaction with syntaxin 5 is inhibited by the binding of the vesicle docking protein p115 to a distal binding site in GM130. The interaction between GM130 and the small GTPase Rab1 is also inhibited by p115 binding. Our findings suggest a mechanism for coupling membrane tethering and fusion at the ER to Golgi intermediate compartment and cis-Golgi, with GM130 playing a central role in linking these processes. Consistent with this hypothesis, we find that depletion of GM130 by RNA interference slows the rate of ER to Golgi trafficking in vivo. The interactions of GM130 with syntaxin 5 and Rab1 are also regulated by mitotic phosphorylation, which is likely to contribute to the inhibition of ER to Golgi trafficking that occurs when mammalian cells enter mitosis.
authors.affiliation: Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom.
authors.forename: Aipo
authors.initials: A
authors.lastname: Diao
authors.forename: Laura
authors.initials: L
authors.lastname: Frost
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Morohashi
authors.forename: Martin
authors.initials: M
authors.lastname: Lowe
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000737:chemistry*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008938:Mitosis; D008954:Models, Biological; D010766:Phosphorylation; D050765:Qa-SNARE Proteins / Q000737:chemistry*; D034622:RNA Interference; D051381:Rats; D064067:Rho Guanine Nucleotide Exchange Factors; D020761:rab1 GTP-Binding Proteins / Q000737:chemistry
chemical_list: D001324:Autoantigens; C097741:Golgin subfamily A member 2; D020662:Guanine Nucleotide Exchange Factors; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D020761:rab1 GTP-Binding Proteins