Synaptophysin

Synaptophysin, a 38 kD glycoprotein, is the major integral membrane protein of synaptic vesicles. Major concentrations of the protein are found in the trans-Golgi region and in the presynaptic vesicles of neurons (brain, spinal cord, retina, neuromuscular junctions) and the smooth-surfaced vesicles of neuro-endocrine cells of the gut, adrenal medulla, pancreatic islets, pheochromocytomas. Synaptophysin is a sensitive quantitative molecular marker of synaptic density and also a useful marker in the identification and characterization of neuronal and neuroendocrine neoplasms of the adrenal medullary, pituitary, thyroid and islet cell tumors, gastrointestinal, bronchial, thymic and pancreatic carcinoid tumors. Immunohistochemistry of synaptophysin has been used in the evaluation of functional bowel disorders, cortical epileptogenesis, schizophrenia and amyotropic lateral sclerosis.