THY-1 IS A COMPONENT COMMON TO MULTIPLE POPULATIONS OF SYNAPTIC VESICLES

Thy-1, a glycosylphosphatidylinositol-linked integral membrane protein of the immunoglobulin superfamily, is a component of both large dense -core and small clear vesicles in PC12 cells. A majority of this prote in, formerly recognized only on the plasma membrane of neurons, is loc alized to regulated secretory vesicles. Thy-1 is also present in synap tic vesicles in rat central nervous system. Experiments on permeabiliz ed PC12 cells demonstrate that antibodies against Thy-1 inhibit the re gulated release of neurotransmitter; this inhibition appears to be ind ependent of any effect on the Ca2+ channel. These findings suggest Thy -1 is an integral component of many types of regulated secretory vesic les, and plays an important role in the regulated vesicular release of neurotransmitter at the synapse.