Argininosuccinate Lyase (ASL)

ASL encodes a member of the lyase 1 family. The encoded protein forms a cytosolic homotetramer and primarily catalyzes the reversible hydrolytic cleavage of argininosuccinate into arginine and fumarate, an essential step in the liver in detoxifying ammonia via the urea cycle. Mutations in this gene result in the autosomal recessive disorder argininosuccinic aciduria, or argininosuccinic acid lyase deficiency. A nontranscribed pseudogene is also located on the long arm of chromosome 22. Alternatively spliced transcript variants encoding different isoforms have been described.The cDNA encodes a deduced protein of 463 amino acids with a predicted molecular mass of 52 kD, and the active enzyme is a homotetramer. The amino acid sequence of the human enzyme shows 56% homology to the yeast enzyme.