Photorespiratory enzyme that catalyzes transamination reactions with multiple substrates, including asparagine. Functions exclusively as a catabolic enzyme in Asn metabolism (PubMed:18235971, PubMed:23098902). Involved in root development during seedling establishment after seed germination by regulating serine homeostasis and acetate conversion (PubMed:31161264). glyoxylate + L-serine = 3-hydroxypyruvate + glycine glyoxylate + L-alanine = glycine + pyruvate L-serine + pyruvate = 3-hydroxypyruvate + L-alanine 3-hydroxypyruvate + L-asparagine = 2-oxosuccinamate + L-serine glyoxylate + L-asparagine = 2-oxosuccinamate + glycine L-asparagine + pyruvate = 2-oxosuccinamate + L-alanine Inhibited by aminooxyacetate and beta-chloro-L-alanine, but not by p-hydroxymercuribenzoate. kcat is 6.4 sec(-1) for L-serine. kcat is 2.86 sec(-1) for L-alanine. Optimum pH is 9.2. Forms homodimers (PubMed:18235971, PubMed:31681359). Interacts with RABGAP22 (PubMed:24505423). Widely expressed. Preferentially expressed in green, leafy tissues, root cortex and epidermis, developing siliques and dry seeds. Up-regulated in roots after treatment with asparagine (PubMed:23098902). Induced in roots by infection with the soil-born fungal pathogen Verticillium longisporum (PubMed:24505423). Induced in roots by abscicic acid (ABA) and salt stress (PubMed:31161264). No visible phenotype under normal growth conditions. Preferentially acts as a serine--glyoxylate aminotransferase in vitro (PubMed:18235971). Seedlings overexpressing AGT1 exhibit increased length of primary roots, increased number of lateral roots and increased tolerance to salt stress (PubMed:31161264). Belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family.