Mint1, a Munc-18-interacting protein, is expressed in insulin-secreting beta-cells.

Munc-18-interacting (Mint) proteins are adaptors involved in regulation of synaptic vesicle exocytosis. We have investigated expression and cellular localization of Mint1 in pancreatic islets with special reference to insulin-secreting beta-cells. Western blotting showed that Mint1 was expressed in hamster (HIT-T15) and rat (RINm5F) beta-cell lines. Mint1 immunoreactivity was preferentially localized to the periphery of individual islet cells. RT-PCR analysis revealed that apart from Mint1, RINm5F cells and rat islets also transcribed the mRNAs for Mint2 and Mint3. Expression of Mint proteins in pancreatic beta-cells suggests a functional role for these proteins in insulin granule exocytosis.