A cytoplasmic vesicle composed of both tubulovesicular and clear core vesicles that transport synaptic vesicle-associated proteins. Proteins carried by synaptic vesicle protein transport vesicles (STVs) include synaptophysin, synapsin Ia, synaptotagmin and synaptobrevin/vesicle-associated membrane protein 2 (VAMP2). STVs are packaged via the trans-Golgi network before being transported through the axon.
Comment:
This term should not be confused with GO:0008021 'synaptic vesicle'. STVs and synaptic vesicles differ both functionally and morphologically. Functionally, STVs are transport vesicles that deliver synaptic vesicle proteins to synapses, while synaptic vesicles are responsible for transmitter release at synapses. Morphologically, synaptic vesicles are very homogeneous, while STVs are very heterogeneous in size and shape. STVs might be a precursor for synaptic vesicles.