 This heteroduplex enzyme is composed of a heavy chain and a light chain, which are derived from a single precursor protein, and is present in tissues involved in absorption and secretion.This enzyme is a member of the gamma-glutamyltransferase protein family, of which many members have not yet been fully characterized.This gene encodes several transcript variants; studies suggest that many transcripts of this gene family may be non-functional or represent pseudogenes.