ASS1

ASS1 encodes argininosuccinate synthase, a predominantly cytosolic homotetrameric ligase that catalyzes the ATP-dependent condensation of L-citrulline and L-aspartate to form argininosuccinate, AMP and diphosphate. Argininosuccinate is then cleaved by ASL to produce arginine and fumarate. ASS1 therefore directly supports hepatic nitrogen disposal through the urea cycle and L-arginine synthesis in other tissues. In endothelial cells, regeneration of arginine from citrulline supports nitric oxide production by nitric oxide synthase. ASS1 activity can be regulated by protein interactions and acetylation, including CLOCK-dependent modification associated with circadian ureagenesis. Peripheral mitochondrial association has been reported in rodent tissues, and nuclear localization has been demonstrated in particular human cell contexts. Pathogenic ASS1 variants cause autosomal recessive citrullinemia type I.

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

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• metabolic_intoxication_decompensation via Citrullinemia Type I