SYNAPSIN I IN NERVE TERMINALS SELECTIVE ASSOCIATION WITH SMALL SYNAPTIC VESICLES

Immunocytochemistry revealed that synapsin I is preferentially (and possibly exclusively) associated with small (40- to 60-nm) synaptic vesicles and not with large (> 60 nm) dense-core vesicles in bovine hypothalamus. These observations may explain why synapsin I is found exclusively in neurons, since small syaptic vesicles are specific to neurons whereas large dense-core vesicles in neurons may be considered the equivalent of secretory organelles in endocrine cells.