Conopressin

Conopressin is a nonapeptide, which is expressed in the central nervous system. It was found to act like a neurotransmitter in mollusks. In 1975, conopressin activity was originally isolated from ganglia of mollusks. It belongs to vasopressin-like peptide family and has a high sequence homology with the mammalian hormone oxytocin (OT). Compressin is composed of three parts: a carboxyl-terminal amidation signal, an endoproteoltytic processing site, and a neurophysin domain. Scientists have identified several structural analogs of its: conopressin- G, T and S.

It is well known that conopressins connect to G-protein coupled receptors to exert their functions. Conopressin stimulates both transient and persistent inward currents in mulluscan neurons, which influences excitability, firing, and the shape of action potential. Moreover, it regulates gill behavior.