Syntaxin 1 (HPC-1) is associated with chromaffin granules

Syntaxin 1 (HPC-1), a component of the receptor for SNAPs (soluble N- ethylmaleimide-sensitive factor attachment proteins), has been implicated in the docking and fusion of synaptic vesicles with the plasma membrane. It was reported that syntaxin 1 in rat brain and chromaffin cells (PC12) is exclusively located on the plasma membrane (Bennett, M. K., Calakos, N., and Scheller, R. H. (1992) Science 257, 255-259; Sollner, T., Bennett, M. K., Whiteheart, S. W., Scheller, R. H., and Rothman, J. E. (1993) Cell 75, 409- 418). By means of biochemical and morphological analyses, we now show that syntaxin 1 is associated with chromaffin granules in the adrenal medulla. This finding raises the possibility that syntaxin 1 in chromaffin cells is a component of vesicle-SNAP receptor as well as one of target-SNAP receptor on the plasma membrane.