argininosuccinate synthetase (citrulline-aspartate ligase, ASS1, ASS)

Function

• amino-acid biosynthesis; L-arginine biosynthesis
• L-arginine from L-ornithine & carbamoyl phosphate: step 2/3
• nitrogen metabolism; urea cycle; argininosuccinate from L-aspartate & L-citrulline: step 1/1

ATP + L-citrulline + L-aspartate
          <-->
AMP + diphosphate + N(omega)-L-argininosuccinate

Structure

• homotetramer
• belongs to the argininosuccinate synthase family, type 1 subfamily

Pathology

• defects in activity results in citrullinemia type 1

Laboratory

• ASS1 gene mutation
• argininosuccinate synthase in amniotic fluid cells
• argininosuccinate synthase in chorionic villus
• argininosuccinate synthase in liver
  • argininosuccinate synthase in liver from fetus
• argininosuccinate synthase in fibroblasts

More general terms

• ligase or synthetase
• urea cycle enzyme

Additional terms

• urea cycle

Database

• UniProt: http://www.uniprot.org/uniprot/P00966.html
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:445
• OMIM: https://mirror.omim.org/entry/215700
• OMIM: https://mirror.omim.org/entry/603470