The Identification of VAMPs in B-Lymphocytes

Abstract

VAMPs (vesicle associated membrane proteins) are vital components for vesicle transport within the cell and exocytosis of materials from the cell. VAMP 1 and 2 are crucial for exocytosis of neurotransmitter while VAMP 3 is more ubiquitous in expression and function and VAMPs 7 and 8, which were once deemed to be endocytosis mediators, are now known to be involved in exocytosis in non-neuronal cells such as pancreatic acinar cells, mast cells and neutrophils. White blood cells other than mast cells and neutrophils have also been examined for VAMP content. Human B-lymphocytes have been found to display VAMP 2 and 3. Our laboratory has determined that VAMP 2 co-localized with immunoglobulin in Human RPMI 1788 cells. This finding was supported by the co-localization of VAMP 2 with the vesicular fraction of rabbit plasmacytoma-like 240 E cells as well. VAMP 3, which was previously identified in human cell lines, was found primarily associated with the plasma membrane fraction in 240 E cells. Since VAMP 7 has been found to be present in other white blood cell lines, we tested 240 E cells for the presence of VAMP 7. Our data confirmed the presence of VAMP 7 via whole cell fluorescence; however, it could not be verified by immunoblot techniques. We conclude that multiple VAMPs are present in plasma cells. VAMP 2 is most likely associated with exocytosis of antibody. VAMP 3 is also most likely involved with a mechanism at the plasma membrane and VAMP 7 may be present in the cell at low quantities with a role in the cell that has yet to be determined.