Amidophosphoribosyltransferase (ATase), also known as glutamine phosphoribosylpyrophosphate amidotransferase (GPAT), is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that in humans is encoded by the PPAT (phosphoribosyl pyrophosphate amidotransferase) gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

ATase is an enzyme that converts α-phosphoribosylpyrophosphate (α-PRPP) into 5-β-phosphoribosylamine. The enzyme uses the ammonia group from the glutamine

Glutamine

Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...

 side-chain. This is the committing step in de novo purine

Purine

A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....

synthesis. It is allosterically inhibited by AMP, GMP, and IMP.

ATase is a member of the purine/pyrimidine phosphoribosyltransferase family. This protein is a regulatory allosteric enzyme that catalyzes the first step of de novo purine nucleotide biosynthesis.

Interactive pathway map

External links