Catalytic component of the GSH degradosomal complex involved in the degradation of glutathione (GSH) and other peptides containing a gamma-glu-X bond. Functions also in a DUG2-DUG3-independent manner as a dipeptidase with high specificity for Cys-Gly and no activity toward tri- or tetrapeptides. Homodimer. Component of the GSH degradosomal complex composed of at least DUG1, DUG2 and DUG3. Accumulation of Cys-Gly dipeptide and enhanced GSH toxicity. Present with 22300 molecules/cell in log phase SD medium. Belongs to the peptidase M20A family.