Citrulline

Citrulline is an intermediate in the urea cycle.

Reaction 1 below occurs in the mitochondrion, but reaction 2 occurs in the cytoplasm.

1. Carbamoyl Phosphate + Ornithine <=> Citrulline + Pi (catalyzed by Ornithine Transcarbamoylase)

2. Citrulline + ATP + Aspartate <=> Argininosuccinate + AMP + PPi (catalyzed by Argininosuccinate Synthetase)

See also: Urea Cycle, Amino Acids Not In Proteins, Ornithine, Aspartate

INTERNET LINK: Urea Cycle and Metabolism of Amino Groups