The localization of VAMP5 in skeletal and cardiac muscle.

Vesicle-associated membrane protein 5 (VAMP5) is a member of the SNARE protein family, which is generally thought to regulate the docking and fusion of vesicles with their target membranes. This study investigated the expression and localization of the VAMP5 protein. Immunoblotting analyses detected the VAMP5 protein in skeletal muscle, heart, spleen, lung, liver, and kidney tissue, but not in brain or small intestine tissue. Through the immunofluorescence microscopy of skeletal muscle, we found that the expression level of VAMP5 varies among fibers. Most of the fibers with high expression levels of VAMP5 were categorized as type IIa fibers on the basis of their myosin heavy chain subtypes. In addition, the expression patterns of VAMP5 and glucose transporter 4 (GLUT4) were similar. In cardiac muscle, we determined that VAMP5 was localized to the vicinity of intercalated discs. These results suggest that VAMP5 plays local roles in membrane trafficking in skeletal and cardiac muscle.