Mammalian Sly1 Regulates Syntaxin 5 Function in Endoplasmic Reticulum to Golgi Transport

doi:10.1074/jbc.271.27.15866

Mammalian Sly1 Regulates Syntaxin 5 Function in Endoplasmic Reticulum to Golgi Transport*

From the Departments of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92130

^§ To whom correspondence should be addressed:
Depts. of Cell and Molecular Biology, The Scripps Research Institute, 10666 N. Torrey Pines Rd., La Jolla, CA 92130.
Tel.: 619-554-2310; Fax: 619-554-6728.

Abstract

Members of the syntaxin gene family are components of protein complexes which regulate vesicle docking and/or fusion during transport of cargo through the secretory pathway of eukaryotic cells. We have previously demonstrated that syntaxin 5 is specifically required for endoplasmic reticulum to Golgi transport (Dascher, C., Matteson, J., and Balch, W. E. (1994) J. Biol. Chem. 269, 29363-29366). To extend these observations we have now cloned a protein from rat liver membranes which forms a native complex with syntaxin 5. We demonstrate that this protein is the mammalian homologue to yeast Sly1p, previously identified as a protein which genetically and biochemically interacts with the small GTPase Ypt1p and Sed5p, proteins involved in docking/fusion in the early secretory pathway of yeast. Using transient expression we find that overexpression of rat liver Sly1 (rSly1) can neutralize the dominant negative effects of excess syntaxin 5 on endoplasmic reticulum to Golgi transport. These results suggest that rSly1 functions to positively regulate syntaxin 5 function.

Footnotes

↵^‡ Recipient of a fellowship grant from the Deutsche Forschungsgemeinschaft.
↵* This work was supported in part by Grant GM 42336 from the National Institutes of Health (to W. E. B.), by Shared Instrumentation Grants RRO7273 and RR08176, and the Lucille P. Markey Charitable Trust. This is TSRI Manuscript Number 10002-CB. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U57687[GenBank].
↵¹ The abbreviations used are:

ER

endoplasmic reticulum

BHK

baby hamster kidney

NRK

normal rat kidney

VSV-G

vesicular stomatitis virus glycoprotein

IgG

immunoglobulin G

PCR

polymerase chain reaction

RACE

rapid amplification of cDNA ends

EST

expressed sequence tag

PAGE

polyacrylamide gel electrophoresis

PMSF

phenylmethylsulfonyl fluoride

CHAPS

3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate

HPLC

high-pressure liquid chromatography

ECL

enhanced chemiluminescence

DTT

dithiothreitol

endo H

endoglycosidase H.
- Received March 28, 1996.
- Revision received April 26, 1996.