Indoleamine 2,3-Dioxygenase 1 is a human gene encoded by the symbol, IDO1. It may also be known as: IDO-1; Indoleamine-pyrrole 2,3-dioxygenase; IDO; INDO. The encoded protein is an enzyme with an amino acid length of 403 and a mass of 45.3 kDa. Other isoforms may exist. Indoleamine 2,3-Dioxygenase 1 is a member of the Indoleamine 2,3-dioxygenase family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog.