Amidophosphoribosyltransferase

• OMIM: 172450
• UniProt: Q06203

The Amidophosphoribosyltransferase ( ATase ), also called GPAT is the enzyme that transfers a ribose of PRPP to glutamine. This reaction step in purine biosynthesis of all living beings is basically fixed, that is, from the products of this and the following reactions can henceforth only be produced IMP. The ATase is localized in the cytosol, occurs in all types of tissue, and requires co-factors as a magnesium and an iron -sulfur cluster.

Catalyzed reaction

H2O    PPi

From PRPP and glutamine 5 - Phosphoribosylamin arises ( PRA) and glutamate. The reaction at equilibrium is shifted by hydrolysis of the diphosphate strongly to the right. As inhibitors act IMP, GMP and AMP.