Synaptic vesicles are uniform, phospholipid-bound organelles that function to store neurotransmitters for release in the synaptic cleft between neurons. They measure about 40 nanometers in diameter; this small size gives them an estimated capacity of only 200 proteins. These proteins are limited to two classes: transport and vesicle trafficking. Some synaptic vesicle and vesicle-associated proteins include synaptophysin, synaptotagmins (SYTs), and synapsins. A variety of antibodies that target these synaptic vesicle proteins are available from a number of suppliers.