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Gene Review

sca  -  scabrous

Drosophila melanogaster

Synonyms: AAA28880, AAF58455, CG17579, Dmel\CG17579, FBpp0086968, ...
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High impact information on sca

  • Here we present in vivo and biochemical evidence that the secreted protein Scabrous associates with Notch, and can stabilize Notch protein at the surface [1].
  • Based on its loss-of-function phenotype, expression pattern, and the predicted structure of its product, a secreted peptide with homology to the fibrinogen gene family, we propose that sca encodes a signal involved in lateral inhibition within individual domains of the developing nervous system [2].
  • During imaginal development, sca is mainly expressed in the R8 photoreceptor precursor cells in the eye imaginal disc and in sensory organ precursor cells in other discs [2].
  • The sca transcription unit is 12 kb and consists of four exons that are joined in a 3.2-kb mRNA [2].
  • During embryogenesis, sca is expressed in a dynamic pattern associated with neural development [2].

Biological context of sca

  • Similar phenotypes showed that sca and gp150 genes act in a common pathway [3].
  • We detail here the dynamic pattern of sca transcript accumulation during embryogenesis and show that mutation of Ubx results in the ectopic transcription of sca in the first abdominal segment [4].
  • This pattern is established during disc development, when clusters rotate through 90 degrees, a process dependent on planar cell polarity and rotation-specific factors such as Nemo and Scabrous [5].
  • In an enhancer trap screen we have isolated several P[lacZ] insertions close to the sca transcription start site [2].
  • Three sites in regulatory regions were associated with female-specific variation in abdominal bristle number, one of which was an SSCP site in the region of the gene associated with regulation of sca in embryonic abdominal segments [6].

Anatomical context of sca


Associations of sca with chemical compounds

  • Using expression in Drosophila Schneider cells, we showed that sca encoded a dimeric glycoprotein which was secreted and found in soluble form in the tissue culture medium [8].
  • The sca protein contained both N- and O-linked carbohydrates and interacted with heparin [8].

Other interactions of sca

  • We show that Dl, a membrane-bound ligand for Notch, can inhibit adjacent cells, in direct contact with the precursor, in the absence of Sca [7].
  • Mosaic analysis found that the gp150 and sca genes were required in different cells from one another [3].
  • We propose that a direct interaction of Ubx with cis-acting elements in sca negatively regulates the gene [4].
  • N and Dl were required to repress ato in the vicinity of R8 cells, whereas sca had effects over several cell diameters [8].
  • The identity of the secreted inhibitor remains elusive but, contrary to previous suggestions, we show that it is not Argos. This Egfr-dependent inhibition acts in parallel to the inhibition of atonal by the secreted protein Scabrous [10].


  1. Scabrous complexes with Notch to mediate boundary formation. Powell, P.A., Wesley, C., Spencer, S., Cagan, R.L. Nature (2001) [Pubmed]
  2. Isolation and expression of scabrous, a gene regulating neurogenesis in Drosophila. Mlodzik, M., Baker, N.E., Rubin, G.M. Genes Dev. (1990) [Pubmed]
  3. Scabrous and Gp150 are endosomal proteins that regulate Notch activity. Li, Y., Fetchko, M., Lai, Z.C., Baker, N.E. Development (2003) [Pubmed]
  4. Homeotic control in Drosophila; the scabrous gene is an in vivo target of Ultrabithorax proteins. Graba, Y., Aragnol, D., Laurenti, P., Garzino, V., Charmot, D., Berenger, H., Pradel, J. EMBO J. (1992) [Pubmed]
  5. Egfr signalling defines a protective function for ommatidial orientation in the Drosophila eye. Brown, K.E., Freeman, M. Development (2003) [Pubmed]
  6. Linkage disequilibrium mapping of molecular polymorphisms at the scabrous locus associated with naturally occurring variation in bristle number in Drosophila melanogaster. Lyman, R.F., Lai, C., MacKay, T.F. Genet. Res. (1999) [Pubmed]
  7. scabrous modifies epithelial cell adhesion and extends the range of lateral signalling during development of the spaced bristle pattern in Drosophila. Renaud, O., Simpson, P. Dev. Biol. (2001) [Pubmed]
  8. The scabrous gene encodes a secreted glycoprotein dimer and regulates proneural development in Drosophila eyes. Lee, E.C., Hu, X., Yu, S.Y., Baker, N.E. Mol. Cell. Biol. (1996) [Pubmed]
  9. The scabrous protein can act as an extracellular antagonist of notch signaling in the Drosophila wing. Lee, E.C., Yu, S.Y., Baker, N.E. Curr. Biol. (2000) [Pubmed]
  10. A primary role for the epidermal growth factor receptor in ommatidial spacing in the Drosophila eye. Baonza, A., Casci, T., Freeman, M. Curr. Biol. (2001) [Pubmed]
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