Amidophosphoribosyltransferase Summary

Amidophosphoribosyltransferase (PPAT, also known as ATase) is a 517-amino acid enzyme that catalyzes the formation of phosphoribosylamine from phosphoribosylpyrophosphate (PRPP) and glutamine (UniProt: Q06203). This reaction represents the first committed step of de novo purine nucleotide biosynthesis, making it essential for DNA and RNA synthesis and cellular energy metabolism.

PPAT functions within purine metabolism, a fundamental pathway supporting nucleic acid synthesis and cellular signaling across all tissues. No specific disease associations are documented in UniProt records, though the protein's role in nucleotide metabolism connects it to processes relevant in neurological contexts.

In Alzheimer's Disease pathology, PPAT shows a modest upregulation in post-mortem AD brain tissue compared to age-matched controls (mean log2 fold-change: +0.5049, Chaparral AD proteomics). This increase was detected via TMT-labeled proteomic analysis across four subcellular fractions (P2, P3, S2, S3) from human post-mortem brain tissue. The elevation of purine synthetic capacity in AD brain may reflect altered nucleotide demands associated with neurodegeneration or compensatory cellular responses.