Vesicular transport events appear to be facilitated by the VAMP/synaptobrevin family of membrane proteins in the vesicle (v-SNAREs) and a heterodimeric complex of syntaxin and SNAP-23/25 family members in the target membrane (t-SNAREs). In this manuscript we examine the tissue distribution and composition of the heterodimeric t-SNARE complexes in adult rodent brain. Analysis of protein extracts from brain regions shows that SNAP-25, syntaxin 1, and 4 are broadly distributed, while SNAP-23, syntaxin 3, and 7 show distinct patterns of expression. Further immunohistochemistry and fractionation studies show that while SNAP-25 is enriched in axons and nerve terminals, SNAP-23 is concentrated in cell bodies. Both SNAP-23 and SNAP-25 associate with the plasma membrane and can be metabolically labeled with [3H] palmitate in AtT-20 cells. Anti-SNAP-25 antibodies co- immunoprecipitate t-SNARE heterodimers from brain extracts that predominantly contain syntaxin 1 and 2. Contrary to results from in vitro binding assays, SNAP-23 was found predominantly associated with syntaxin 3. These observations suggest that t-SNARE, heterodimer composition is governed more by SNARE expression and localization than by simple protein-protein affinity.
|Number of pages||14|
|State||Published - Jun 12 1999|
Bibliographical noteFunding Information:
We thank Ramona Alcala for technical assistance and Dr. John Slevin for helpful discussions. We also thank Dr. Mark K. Bennet, Dr. Reinhard Jahn, and Dr. A.L. Hubbard for the generous gifts of their antibodies. We thank Paula Lemons, Atish Mukerjee, and Audrey Bernstein for their comments on this manuscript. This work is supported by a grant from the National Institutes of Health to S.W.W.; S.L.M. is supported by the Welcome Trust.
- Membrane trafficking
ASJC Scopus subject areas
- Neuroscience (all)
- Molecular Biology
- Clinical Neurology
- Developmental Biology