Synaptophysin is an integral transmembrane protein with four transmembrane domains. The Protein plays a role in endocytosis of synaptic vesicles in mammalian central neurons. It is present in all neurons, all types of pancreastic islet cells and paraganglia cells. Additional, it is expressed in almost all neuroendocrine neoplasms. Synaptophysin is helpful for the detection of tumors with neuronal and neuroendocrine differentiation.

[1] Kwon SE and Chapman ER (2011) Synaptophysin regulates the kinetics of synaptic vesicle endocytosis in central neurons. Neuron. 70(5):847-54.
[2] Gould VE, Wiedenmann B, Lee I, et al. (1987) Synaptophysin expression in neuroendocrine neoplasms as determined by immunocytochemistry. Am J Pathol. 126(2): 243Ð257.