Catalyzes the glutamate:glyoxylate (GGT or GGAT), alanine:glyoxylate (AGT), alanine:2-oxoglutarate (AKT) and glutamate:pyruvate (GPT) aminotransferase reactions in peroxisomes. Required for abscisic acid (ABA)- and stress-mediated responses in an H(2)O(2)-dependent manner. Functions as a photorespiratory aminotransferase that modulates amino acid content during photorespiration (GGAT activity); promotes serine, glycine and citrulline metabolism in response to light. 2-oxoglutarate + L-alanine = L-glutamate + pyruvate glyoxylate + L-alanine = glycine + pyruvate 2-oxoglutarate + glycine = glyoxylate + L-glutamate Amino-acid biosynthesis; glycine biosynthesis; glycine from glyoxylate: step 1/1. Photosynthesis; C4 acid pathway. Amino-acid degradation; L-alanine degradation via transaminase pathway; pyruvate from L-alanine: step 1/1. Homodimer. Mostly expressed in leaves, and, to a lower extent, in shoots, stems, flowers, seedlings and green siliques. Down regulated in the dark. Slightly induced upon low-oxygen stress in shoots. The N-terminus is blocked. Reduced growth. Loss of alanine aminotransferase activity and increased light sensitivity alleviated by addition of sucrose and rescued by high CO(2). Higher H(2)O(2) levels in light conditions. Greater root growth in low water potential and upon NaCl-stress. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family. Alanine aminotransferase subfamily.