EXPRESSION OF THE SYNAPTIC VESICLE PROTEINS VAMPS SYNAPTOBREVIN-1 ANDVAMPS/SYNAPTOBREVIN-2 IN NONNEURAL TISSUES/

The VAMPs/synaptobrevins (Vp/Sybs) are small integral membrane protein s. Two isoforms, Vp/Syb 1 and Vp/Syb 2, are considered to be specific to neural tissue. They are associated with synaptic vesicles and are b elieved to play an important role in neurotransmitter release. A third isoform, cellubrevin, has recently been found in non-neural tissues. We now report that the distribution of Vp/Syb 1 and Vp/Syb 2 is wider than previously thought. RNA transcripts for both Vp/Syb 1 and Vp/Syb 2 were found in rat skeletal muscle and in several other rat non-neura l tissues, and antibodies specific for Vp/Syb 2 detected a protein in the endoplasmic reticulum-Golgi area of skeletal muscle. Thus Vp/Sybs 1 and 2 are not restricted to the nervous system but appear to be co-e xpressed with cellubrevin in many different tissues. This redundancy o f Vp/Sybs in a single cell may be required to control the specificity of vesicle-target interaction in the several pathways of intracellular vesicle traffic that are operative within each cell.