ATP + L-aspartate + L-citrulline = 2-(N(omega)-L-arginino)succinate + AMP + diphosphate + H(+) Amino-acid biosynthesis; L-arginine biosynthesis; L-arginine from L-ornithine and carbamoyl phosphate: step 2/3. Homotetramer. The monomer is composed of two major structural domains: a nucleotide-binding domain and a catalytic/multimerization domain. Binding of ATP results in a large rigid body conformational change of the nucleotide binding domain. Belongs to the argininosuccinate synthase family. Type 2 subfamily.