ASS1

Developmental stage

Expressed in fetal liver and kidney.

Function

One of the enzymes of the urea cycle, the metabolic pathway transforming neurotoxic amonia produced by protein catabolism into inocuous urea in the liver of ureotelic animals. Catalyzes the formation of arginosuccinate from aspartate, citrulline and ATP and together with ASL it is responsible for the biosynthesis of arginine in most body tissues.

Involvement in disease

Citrullinemia 1

CTLN1

The classic form of citrullinemia, an autosomal recessive disease characterized primarily by elevated serum and urine citrulline levels. Ammonia intoxication is another manifestation. It is a disorder of the urea cycle, usually manifesting in the first few days of life. Affected infants appear normal at birth, but as ammonia builds up in the body they present symptoms such as lethargy, poor feeding, vomiting, seizures and loss of consciousness. Less commonly, a milder form can develop later in childhood or adulthood.

None

The disease is caused by variants affecting the gene represented in this entry.

Pathway

Amino-acid biosynthesis; L-arginine biosynthesis; L-arginine from L-ornithine and carbamoyl phosphate: step 2/3.

Nitrogen metabolism; urea cycle; (N(omega)-L-arginino)succinate from L-aspartate and L-citrulline: step 1/1.

Post-translational modifications

Acetylated by CLOCK in a circadian manner which negatively regulates its enzyme activity. Deacetylated by histone deacetylases.

Sequence similarities

Belongs to the argininosuccinate synthase family. Type 1 subfamily.

Tissue specificity

Expressed in adult liver.

Cellular localization

• Cytoplasm
• Cytosol

Alternative names

• Argininosuccinate synthase
• Citrulline--aspartate ligase
• ASS
• ASS1

Database links

• entrezGene:445
• omim:603470
• swissprot:P00966

Target type

Proteins

Molecular weight

46530Da