Serotonin binding proteins "SBP": target proteins and tool for in vitro neurotoxicity studies.

1. Serotonin binding proteins (SBP, 45 and 56 kDa) were initially believed to store, transport and/or protect serotonin in serotonergic neurons and, later, to play a catecholamine "housekeeping" function as well. 2. Monoamines do not form coordination bonds with a preformed iron-SBP complex, as initially believed. Instead, metals oxidise the monoamines either directly (manganese, copper) or via oxygen free radical formation (iron) and the oxidation products bind covalently to SBP. 3. SBP are not involved in the housekeeping of monoamines and actin is likely to represent the 45 kDa form. 4. SBP are targets of catecholamine and serotonin-related neurotoxins and monoamine-SBP binding could represent an in vitro model for neurotoxicity.