Catalyzes two non-sequential steps in de novo AMP synthesis: converts (S)-2-(5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamido)succinate (SAICAR) to fumarate plus 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide, and thereby also contributes to de novo IMP synthesis, and converts succinyladenosine monophosphate (SAMP) to AMP and fumarate. N(6)-(1,2-dicarboxyethyl)-AMP = AMP + fumarate (2S)-2-[5-amino-1-(5-phospho-beta-D-ribosyl)imidazole-4-carboxamido]succinate = 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole-4-carboxamide + fumarate The enzyme reaction kinetics indicate cooperativity between subunits. Purine metabolism; AMP biosynthesis via de novo pathway; AMP from IMP: step 2/2. Purine metabolism; IMP biosynthesis via de novo pathway; 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide from 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate: step 2/2. Homotetramer. Residues from neighboring subunits contribute catalytic and substrate-binding residues to each active site. Ubiquitously expressed. Both isoforms are produced by all tissues. Isoform 2 is 10-fold less abundant than isoform 1. The disease is caused by variants affecting the gene represented in this entry. Lacks enzymatic activity. Belongs to the lyase 1 family. Adenylosuccinate lyase subfamily. Truncated N-terminus. Truncated N-terminus. Adenylosuccinate lyase mutations database