Molecular cloning of the transport proteins involved in packaging monoamines and ACh into secretory vesicles has implicated their activity in neural degeneration as well as signaling. Future studies will explore further the mechanism of active transport, its regulation, and the membrane trafficking of the proteins with the long-term goal of understanding how the regulation of transmitter release and, in particular, quantal size influences information processing and behavior. In addition, the bioenergetics of vesicular GABA and glutamate transport suggests that the proteins responsible for these activities may belong to a distinct gene family.