|
||
J. Cell Biol.,
Volume 141, Number 7, June 29, 1998 1489-1502


* Howard Hughes Medical Institute, Department of Molecular and Cellular Physiology, Stanford University School of Medicine,
Stanford, California 94305-5428; and ER-to-Golgi transport, and perhaps intraGolgi transport involves a set of interacting soluble
N-ethylmaleimide-sensitive factor attachment protein
receptor (SNARE) proteins including syntaxin 5, GOS-28, membrin, rsec22b, and rbet1. By immunoelectron
microscopy we find that rsec22b and rbet1 are enriched
in COPII-coated vesicles that bud from the ER and
presumably fuse with nearby vesicular tubular clusters
(VTCs). However, all of the SNAREs were found on
both COPII- and COPI-coated membranes, indicating
that similar SNARE machinery directs both vesicle
pathways. rsec22b and rbet1 do not appear beyond the
first Golgi cisterna, whereas syntaxin 5 and membrin
penetrate deeply into the Golgi stacks. Temperature shifts reveal that membrin, rsec22b, rbet1, and syntaxin
5 are present together on membranes that rapidly recycle between peripheral and Golgi-centric locations.
GOS-28, on the other hand, maintains a fixed localization in the Golgi. By immunoprecipitation analysis, syntaxin 5 exists in at least two major subcomplexes:
one containing syntaxin 5 (34-kD isoform) and GOS-28, and another containing syntaxin 5 (41- and 34-kD
isoforms), membrin, rsec22b, and rbet1. Both subcomplexes appear to involve direct interactions of each SNARE with syntaxin 5. Our results indicate a central
role for complexes among rbet1, rsec22b, membrin, and
syntaxin 5 (34 and 41 kD) at two membrane fusion interfaces: the fusion of ER-derived vesicles with VTCs,
and the assembly of VTCs to form cis-Golgi elements.
The 34-kD syntaxin 5 isoform, membrin, and GOS-28
may function in intraGolgi transport.
Medical School, University of Utrecht, 3584CX Utrecht, The Netherlands
This article has been cited by other articles:
|
|