gamma-Glutamylisoleucine is a dipeptide composed of gamma-glutamate and isoleucine, and is a proteolytic breakdown product of larger proteins. It belongs to the family of N-acyl-alpha amino acids and derivatives. These are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. gamma-Glutamylisoleucine is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signaling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis. It is found in urine.