title: ER to Golgi transport: Requirement for p115 at a pre-Golgi VTC stage.
abstract: The membrane transport factor p115 functions in the secretory pathway of mammalian cells. Using biochemical and morphological approaches, we show that p115 participates in the assembly and maintenance of normal Golgi structure and is required for ER to Golgi traffic at a pre-Golgi stage. Injection of antibodies against p115 into intact WIF-B cells caused Golgi disruption and inhibited Golgi complex reassembly after BFA treatment and wash-out. Addition of anti-p115 antibodies or depletion of p115 from a VSVtsO45 based semi-intact cell transport assay inhibited transport. The inhibition occurred after VSV glycoprotein (VSV-G) exit from the ER but before its delivery to the Golgi complex, and resulted in VSV-G protein accumulating in peripheral vesicular tubular clusters (VTCs). The p115-requiring step of transport followed the rab1-requiring step and preceded the Ca(2+)-requiring step. Unexpectedly, mannosidase I redistributed from the Golgi complex to colocalize with VSV-G protein arrested in pre-Golgi VTCs by p115 depletion. Redistribution of mannosidase I was also observed in cells incubated at 15 degrees C. Our data show that p115 is essential for the translocation of pre-Golgi VTCs from peripheral sites to the Golgi stack. This defines a previously uncharacterized function for p115 at the VTC stage of ER to Golgi traffic.
authors.affiliation: Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: C
authors.initials: C
authors.lastname: Alvarez
authors.forename: H
authors.initials: H
authors.lastname: Fujita
authors.forename: A
authors.initials: A
authors.lastname: Hubbard
authors.forename: E
authors.initials: E
authors.lastname: Sztul
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D006056:Golgi Apparatus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D008361:Mannosidases / Q000378:metabolism; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism; D015388:Organelles / Q000378:metabolism; D051381:Rats; D013696:Temperature; D013997:Time Factors; D033921:Vesicular Transport Proteins; D014759:Viral Envelope Proteins / Q000378:metabolism; D020761:rab1 GTP-Binding Proteins / Q000276:immunology / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; C028391:G protein, vesicular stomatitis virus; D000077614:Golgi Matrix Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; D014759:Viral Envelope Proteins; C091580:vesicular transport factor p115; D020126:Brefeldin A; D017351:N-Acetylglucosaminyltransferases; D008361:Mannosidases; C046090:mannosyl-oligosaccharide 1,2-alpha-mannosidase; C038829:mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase; D020761:rab1 GTP-Binding Proteins; D002118:Calcium