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Gene Review

pr  -  purple

Drosophila melanogaster

Synonyms: 38B.9, 6-pyruvoyl tetrahydrobiopterin synthase, CG16784, Dmel\CG16784, PTP synthase, ...
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Disease relevance of pr

  • The new catalytic function of E. coli PTPS does not imply any physiological role, because sepiapterin is not an endogenous substrate of the organism [1].

High impact information on pr

  • We show here that sepiapterin synthase activity is 30 percent of normal in pr and prbw, two naturally occurring alleles of purple, and is restored to nearly normal levels by the suppressor su(s)2 [2].
  • A heterozygote of two newly induced alleles of pr has even lower enzyme activity (less than 10 percent) [2].
  • Only a few mutations cause it to accumulate, viz. cardinal (cd), dark red brown (drb), Henna-recessive (Hnr), purple (pr), Punch2 (Pu2), Punch-Grape (PuGr), and scarlet (st) [3].
  • The heat-stable enzyme can be replaced by sepiapterin synthase A, a previously purified enzyme required for the Mg2+-dependent conversion of H2-NTP to an unstable compound that appears to be 6-pyruvoyltetrahydropterin (pyruvoyl-H4-pterin) [4].
  • Viable mutant alleles of purple (pr), such as prbw, exhibit mutant eye colors [5].

Biological context of pr

  • The pr gene was cloned to explore the mechanism of this suppression. pr produces two PTP synthase mRNAs: one constitutively from a distal promoter and one in late pupae and young adult heads from a proximal promoter [5].
  • We have analyzed two tandem promoters, separated by only about 400 bp, of the purple (pr) gene of Drosophila melanogaster, by fusing them to the firefly luciferase reporter gene and employing a transient expression assay with Drosophila S2 cells [6].

Associations of pr with chemical compounds


Analytical, diagnostic and therapeutic context of pr


  1. Escherichia coli 6-pyruvoyltetrahydropterin synthase ortholog encoded by ygcM has a new catalytic activity for conversion of sepiapterin to 7,8-dihydropterin. Woo, H.J., Hwang, Y.K., Kim, Y.J., Kang, J.Y., Choi, Y.K., Kim, C.G., Park, Y.S. FEBS Lett. (2002) [Pubmed]
  2. Mechanism of suppression in Drosophila: control of sepiapterin synthase at the purple locus. Yim, J.J., Grell, E.H., Jacobson, K.B. Science (1977) [Pubmed]
  3. Xanthurenic acid 8-O-beta-D-glucoside, a novel tryptophan metabolite in eye-color mutants of Drosophila melanogaster. Ferré, J., Real, M.D., Ménsua, J.L., Jacobson, K.B. J. Biol. Chem. (1985) [Pubmed]
  4. Purification and properties of the enzymes from Drosophila melanogaster that catalyze the conversion of dihydroneopterin triphosphate to the pyrimidodiazepine precursor of the drosopterins. Wiederrecht, G.J., Brown, G.M. J. Biol. Chem. (1984) [Pubmed]
  5. Structure and expression of wild-type and suppressible alleles of the Drosophila purple gene. Kim, N., Kim, J., Park, D., Rosen, C., Dorsett, D., Yim, J. Genetics (1996) [Pubmed]
  6. An analysis of two tandem promoters of the Drosophila purple gene. Baek, G., Yoon, S., Jeon, M.J., Han, S., Yim, J., Baek, K., Yoon, J., Han, K. Mol. Cells (1998) [Pubmed]
  7. Gene expression in adult metafemales of Drosophila melanogaster. Birchler, J.A., Hiebert, J.C., Krietzman, M. Genetics (1989) [Pubmed]
  8. Mechanism of suppression in Drosophila. V. Localization of the purple mutant of Drosophila melanogaster in the pteridine biosynthetic pathway. Wilson, T.G., Jacobson, K.B. Biochem. Genet. (1977) [Pubmed]
  9. Purification and characterization of 6-pyruvoyl-tetrahydropterin synthase from Drosophila melanogaster. Park, Y.S., Kim, J.H., Jacobson, K.B., Yim, J.J. Biochim. Biophys. Acta (1990) [Pubmed]
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