[Amidophosphoribosyltransferase].

Amidophosphoribosyltransferase (ATase) is the supposed regulatory allosteric enzyme of de novo purine nucleotide biosynthesis. ATase cDNAs and genomic DNAs were cloned from 15 different species. The chicken, rat, and human ATase genes and AIRC (aminoimidazole ribonucleotide carboxylase) genes are closely linked and divergently transcribed from an intergenic regions of 0.2-0.6 kb. The crystal structure of B. subtilis ATase was determined. The ATase tetramer is a doughnut-shaped molecule and each ATase subunit is organized in two domains of approximately equal size. The four [4 Fe-4 S] clusters are located at the corners of the tetramer. The activity of ATase is regulated positively by PRPP and negatively by GMP and AMP.