mRNA expression of membrane-fusion-related proteins in rat parotid gland.

The soluble N-ethylmaleimide-sensitive fusion (NSF) attachment protein (SNAP) receptor (SNARE) hypothesis has been applied to exocytosis in salivary glands. The expression of SNARE proteins has not been well investigated in the parotid gland. In this study, the mRNA expression of SNAREs and membrane-fusion-related proteins were investigated in the rat parotid by reverse transcriptase-polymerase chain reaction (RT-PCR). All syntaxins except syntaxin 1, and the vesicle-associated membrane proteins (VAMP) except VAMP-7, NSF, SNAP-23 and alpha-SNAP, were expressed for the SNAREs in rat parotid. Synaptotagmins 3, 4 and 11, Munc18s (1, 2 and 3), syncollin, prenylated Rab acceptor (PRA1), zygin 1, pantophysin and cellugyrin, which are the other membrane-fusion-related proteins, were also detected, but neither Rim nor rabphilin 3A, which have high specificity of binding to Rab 3A, were found. mRNA expressions of many SNAREs and of the membrane-fusion-proteins suggest novel interactions for the regulation of salivary exocytosis.