A new gene in Drosophila melanogaster, Ravus, the phantom of the modifier of position-effect variegation Su(var)3-7

Int J Dev Biol. 2002 Jan;46(1):167-71.


In a search for homologues of the dominant modifier of position-effect variegation Su(var)3-7, we have identified one ORF in Drosophila melanogaster. The 359 amino acid deduced protein is much shorter than the 1169 amino acid protein Su(var)3-7. Surprisingly, the two genes are very close to each other at 87E on the polytene chromosome map, and are transcribed divergently. The triplet coding for the N-terminus amino acid of the new gene lies only 368 base pairs from the start of transcription of Su(var)3-7. This opposite orientation of the homologue has led us to name it Ravus. The N-terminus of the Ravus protein contains only one of the seven unusual zinc fingers of Su(var)3-7. A second region of similarity encodes an acidic domain. Finally, there is a block of high similarity near the C-terminus of the two proteins. It corresponds to a new conserved protein domain, BESS, found also in the BEAF and Stonewall Drosophila proteins. We have constructed a tagged Ravus protein, and have expressed it as a heat-shock inducible transgene. Ravus associates in vivo with polytene chromosomes but, in contrast to the heterochromatin-associated protein Su(var)3-7, does not show specificity for the chromocenter. Ravus does not seem either to modify the genomic silencing of position-effect variegation, as over-expression of the transgene does not affect the variegated phenotype of a number of rearrangements tested.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chromosomal Proteins, Non-Histone / biosynthesis
  • Chromosomal Proteins, Non-Histone / genetics*
  • DNA-Binding Proteins / genetics*
  • Drosophila Proteins / biosynthesis
  • Drosophila Proteins / genetics*
  • Drosophila melanogaster / genetics*
  • Expressed Sequence Tags
  • Heterochromatin / chemistry
  • Models, Genetic
  • Molecular Sequence Data
  • Mutation
  • Open Reading Frames
  • Phenotype
  • Sequence Homology, Amino Acid
  • Transgenes


  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Heterochromatin
  • Ravus protein, Drosophila
  • Su(var)3-7 protein, Drosophila