Identification of a Novel Syntaxin- and Synaptobrevin/VAMP-binding Protein, SNAP-23, Expressed in Non-neuronal Tissues

doi:10.1074/jbc.271.23.13300

Identification of a Novel Syntaxin- and Synaptobrevin/VAMP-binding Protein, SNAP-23, Expressed in Non-neuronal Tissues*

From the Experimental Immunology Branch, NCI, National Institutes of Health, Bethesda, Maryland 20892

^§ To whom correspondence should be addressed:
Bldg. 10, Rm. 4B17, National Institutes of Health, Bethesda, MD 20892.
Tel.: 301-496-7177; Fax: 301-496-0887.

Abstract

The specificity of vesicular transport is regulated, in part, by the interaction of a vesicle-associated membrane protein termed synaptobrevin/VAMP with a target compartment membrane protein termed syntaxin. These proteins, together with SNAP-25 (synaptosome-associated protein of 25 kDa), form a complex which serves as a binding site for the general membrane fusion machinery. Synaptobrevin/VAMP and syntaxin are ubiquitously expressed proteins and are believed to be involved in vesicular transport in most (if not all) cells. However, SNAP-25 is present almost exclusively in the brain, suggesting that a ubiquitously expressed homolog of SNAP-25 exists to facilitate transport vesicle/target membrane fusion in other tissues. Using the yeast two-hybrid system, we have identified a 23-kDa protein from human B lymphocytes (termed SNAP-23) that binds tightly to multiple syntaxins and synaptobrevins/VAMPs in vitro. SNAP-23 is 59% identical with SNAP-25. Unlike SNAP-25, SNAP-23 was expressed in all tissues examined. These findings suggest that SNAP-23 is an essential component of the high affinity receptor for the general membrane fusion machinery and an important regulator of transport vesicle docking and fusion in all mammalian cells.

Footnotes

↵^‡ Fellow of the Howard Hughes Medical Institute-National Institutes of Health Research Scholars Program.
↵* 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) U55936[GenBank].
↵¹ The abbreviations used are:

NSF

N-ethylmaleimide-sensitive fusion protein

SNAP

soluble NSF attachment protein

VAMP

vesicle-associated membrane protein

SNAP-25

synaptosome-associated protein of 25 kDa

SNARE

SNAP receptor

GAPDH

glyceraldehyde-3-phosphate dehydrogenase

GST

glutathione S-transferase.
- Received March 20, 1996.