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Gene Review

PPAT  -  phosphoribosyl pyrophosphate amidotransferase

Homo sapiens

Synonyms: ATASE, ATase, Amidophosphoribosyltransferase, GPAT, Glutamine phosphoribosylpyrophosphate amidotransferase, ...
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Disease relevance of PPAT


High impact information on PPAT

  • The three-dimensional structures of tryptophan synthase, carbamoyl phosphate synthetase, glutamine phosphoribosylpyrophosphate amidotransferase, and asparagine synthetase have revealed the relative locations of multiple active sites within these proteins [4].
  • Acyl-CoA:glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first step during de novo synthesis of triacylglycerol [5].
  • Although the mitochondrial-associated GPAT has been cloned and extensively characterized, the molecular identity of the endoplasmic reticulum (ER)-associated GPAT, which accounts for the majority of total GPAT activity in most tissues, has remained elusive [5].
  • Ectopic expression of GPAT3 leads to a significant increase in N-ethylmaleimide-sensitive GPAT activity, whereas acyltransferase activity toward a variety of other lysophospholipids, as well as neutral lipid substrates, is not altered [5].
  • A substantial loss of GPAT activity in 3T3-L1 adipocytes was achieved by reducing GPAT3 mRNA levels through GPAT3-specific siRNA knockdown [5].

Biological context of PPAT


Anatomical context of PPAT

  • Confocal microscopy of CHO and HEK293 cells transfected with the GPAT-FLAG construct showed that GPAT was located correctly in mitochondria and was not present elsewhere in the cell [9].
  • To test this hypothesis, we overexpressed mitochondrial GPAT in Chinese hamster ovary (CHO) cells [9].
  • Reduced plasma FFA availability increases net triacylglycerol degradation, but not GPAT or HSL activity, in human skeletal muscle [10].
  • We showed, for the first time, that anti-CD3 stimulation in rat splenic T-lymphocytes selectively increased mitochondrial glycerol-3-phosphate acyltransferase (GPAT) activity [11].
  • The enzyme in chloroplasts is soluble and uses acyl-(acyl-carrier protein) as the acyl donor, whereas the enzymes in the mitochondria and the cytoplasm are bound to membranes and use acyl-CoA as the acyl donor. cDNAs for GPAT of chloroplasts have been cloned from several plants, and the gene for the enzyme has been cloned from Arabidopsis thaliana [12].

Associations of PPAT with chemical compounds


Other interactions of PPAT

  • The human genes GPAT, encoding the amidotransferase, and AIRC, encoding a bifunctional enzyme for steps six and seven in the pathway, were cloned and characterized [6].
  • Role of NRF-1 in bidirectional transcription of the human GPAT-AIRC purine biosynthesis locus [7].
  • Cys-1 and Asp-33 are cognate to residues Cys-1 and Asp-29 in glutamine phosphoribosylpyrophosphate amidotransferase which have been proposed to be members of a catalytic triad responsible for mediating nitrogen transfer in this enzyme (Mei, B., and Zalkin, H. (1989) J. Biol. Chem. 264, 16613-16619) [16].

Analytical, diagnostic and therapeutic context of PPAT

  • Genetic engineering of the unsaturation of fatty acids has been achieved by manipulation of the cDNA for the GPAT found in chloroplasts and has allowed modification of the ability of tobacco to tolerate chilling temperatures [12].


  1. Identification and characterization of the gene encoding the human phosphopantetheine adenylyltransferase and dephospho-CoA kinase bifunctional enzyme (CoA synthase). Aghajanian, S., Worrall, D.M. Biochem. J. (2002) [Pubmed]
  2. Inhibition of glycerol-3-phosphate acyltransferase as a potential treatment for insulin resistance and type 2 diabetes. Thuresson, E.R. Current opinion in investigational drugs (London, England : 2000) (2004) [Pubmed]
  3. Serodiagnosis of strongyloidiasis. The application and significance. Sato, Y., Kobayashi, J., Shiroma, Y. Rev. Inst. Med. Trop. Sao Paulo (1995) [Pubmed]
  4. Channeling of substrates and intermediates in enzyme-catalyzed reactions. Huang, X., Holden, H.M., Raushel, F.M. Annu. Rev. Biochem. (2001) [Pubmed]
  5. Molecular identification of microsomal acyl-CoA:glycerol-3-phosphate acyltransferase, a key enzyme in de novo triacylglycerol synthesis. Cao, J., Li, J.L., Li, D., Tobin, J.F., Gimeno, R.E. Proc. Natl. Acad. Sci. U.S.A. (2006) [Pubmed]
  6. Two genes for de novo purine nucleotide synthesis on human chromosome 4 are closely linked and divergently transcribed. Brayton, K.A., Chen, Z., Zhou, G., Nagy, P.L., Gavalas, A., Trent, J.M., Deaven, L.L., Dixon, J.E., Zalkin, H. J. Biol. Chem. (1994) [Pubmed]
  7. Role of NRF-1 in bidirectional transcription of the human GPAT-AIRC purine biosynthesis locus. Chen, S., Nagy, P.L., Zalkin, H. Nucleic Acids Res. (1997) [Pubmed]
  8. The Plasmodium falciparum PfGatp is an endoplasmic reticulum membrane protein important for the initial step of malarial glycerolipid synthesis. Santiago, T.C., Zufferey, R., Mehra, R.S., Coleman, R.A., Mamoun, C.B. J. Biol. Chem. (2004) [Pubmed]
  9. Mitochondrial glycerol phosphate acyltransferase directs the incorporation of exogenous fatty acids into triacylglycerol. Igal, R.A., Wang, S., Gonzalez-Baró, M., Coleman, R.A. J. Biol. Chem. (2001) [Pubmed]
  10. Reduced plasma FFA availability increases net triacylglycerol degradation, but not GPAT or HSL activity, in human skeletal muscle. Watt, M.J., Holmes, A.G., Steinberg, G.R., Mesa, J.L., Kemp, B.E., Febbraio, M.A. Am. J. Physiol. Endocrinol. Metab. (2004) [Pubmed]
  11. Aging reduces glycerol-3-phosphate acyltransferase activity in activated rat splenic T-lymphocytes. Collison, L.W., Kannan, L., Onorato, T.M., Knudsen, J., Haldar, D., Jolly, C.A. Biochim. Biophys. Acta (2005) [Pubmed]
  12. Glycerol-3-phosphate acyltransferase in plants. Murata, N., Tasaka, Y. Biochim. Biophys. Acta (1997) [Pubmed]
  13. Synthesis and analysis of potential prodrugs of coenzyme A analogues for the inhibition of the histone acetyltransferase p300. Cebrat, M., Kim, C.M., Thompson, P.R., Daugherty, M., Cole, P.A. Bioorg. Med. Chem. (2003) [Pubmed]
  14. Enzymatic and cellular study of a serotonin N-acetyltransferase phosphopantetheine-based prodrug. Hwang, Y., Ganguly, S., Ho, A.K., Klein, D.C., Cole, P.A. Bioorg. Med. Chem. (2007) [Pubmed]
  15. A stable carbocyclic analog of 5-phosphoribosyl-1-pyrophosphate to probe the mechanism of catalysis and regulation of glutamine phosphoribosylpyrophosphate amidotransferase. Kim, J.H., Wolle, D., Haridas, K., Parry, R.J., Smith, J.L., Zalkin, H. J. Biol. Chem. (1995) [Pubmed]
  16. Glutamine-dependent nitrogen transfer in Escherichia coli asparagine synthetase B. Searching for the catalytic triad. Boehlein, S.K., Richards, N.G., Schuster, S.M. J. Biol. Chem. (1994) [Pubmed]
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