Alanine Glyoxylate Aminotransferase (AGXT)

Serine--pyruvate aminotransferase is an enzyme expressed only in the liver and the protein is localized mostly in the peroxisomes, where it is involved in glyoxylate detoxification. Mutations in this gene, some of which alter subcellular targeting, have been associated with type I primary hyperoxaluria.The human peroxisomal AGT showed about 78% amino acid sequence identity with rat mitochondrial AGT. The putative pyridoxal phosphate-binding lysine residue at position 209 is conserved. A comparison of the 5-prime sequences indicated that the N-terminal 22 amino acids of the rat translation product are absent from the human protein. The loss of this mitochondrial targeting sequence (MTS) signal during evolution may partly explain the species differences in intracellular localization of AGT.