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Gene Review

if  -  inflated

Drosophila melanogaster

Synonyms: CG9623, CT27194, Dmel\CG9623, If, Integrin alpha-PS2, ...
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Psychiatry related information on if


High impact information on if

  • We report the characterization of a chromosomal integrin gene that encodes the Drosophila PS2 alpha subunit [2].
  • We establish that the position-specific antigen 2 (PS2), a Drosophila cell surface glycoprotein complex, is an invertebrate member of the vertebrate fibronectin receptor (integrin) family [3].
  • We suggest that PS2, like vertebrate fibronectin receptors, mediates changes in cell shape and cell-extracellular matrix adhesion by binding to a basement membrane protein [3].
  • A particularly intriguing pattern of expression is found in the mature wing imaginal disc, where the PS1 integrin is expressed primarily on the presumptive dorsal wing epithelium, and the PS2 integrin is found almost exclusively on the ventral epithelium [4].
  • Two alpha subunits, which form heterodimers with the same betaPS subunit, are expressed in complementary tissues in the Drosophila embryo, with alphaPS1 expressed in the epidermis and endoderm, and alphaPS2 expressed in the mesoderm [5].

Biological context of if

  • In a variety of genetic tests, these alleles behave similarly to ifk27e, which makes no detectable alpha PS2, and all three alleles display the same embryonic phenotype [6].
  • PS2 integrin requirements in Drosophila embryo and wing morphogenesis [6].
  • zipper Nonmuscle myosin-II functions downstream of PS2 integrin in Drosophila myogenesis and is necessary for myofibril formation [7].
  • Unlike null alleles, the three antimorphic mutants are synthetically lethal in double heterozygotes with an inflated (alphaPS2) null allele, and they fail to complement very weak, otherwise viable alleles of myospheroid [8].
  • Using the GAL4 system, we are able to rescue fully the embryonic lethality of an alphaPS2 null mutation with a UAS-alphaPS2 transgene, but only partially with a UAS-alphaPS1 gene, due to partial rescue of both muscle and midgut phenotypes [5].

Anatomical context of if

  • In keeping with this, we demonstrate that a PS2 mutant that specifically disrupts myofibril formation is unable to mediate proper localization of nonmuscle myosin-II at the muscle termini [7].
  • PS1 expression is at the muscle ends and also in the long epidermal processes that connect the developing muscle fibers to their sites of attachment in the epidermis, while PS2 expression is restricted to the muscle ends [9].
  • During myogenesis, PS2alpha is detected transiently in imaginal myoblasts that fuse with persistent larval muscles to give rise to the Dorsal Longitudinal Muscles (DLMs), but not in myoblasts that fuse de novo to give rise to the Dorso Ventral Muscles [9].
  • Tiggrin is a novel extracellular matrix ligand for the Drosophila PS2 integrins [10].
  • The functions of PS1 and PS2 are specific in the two tissues, endoderm and mesoderm, since they cannot substitute for each other [11].

Associations of if with chemical compounds

  • Nonequivalent requirements for PS1 and PS2 integrin at cell attachments in Drosophila: genetic analysis of the alpha PS1 integrin subunit [12].
  • The transition from PSI to early metamorphic phase (PS2 and upwards), induced by rapid elevation in endogenous steroid hormone ecdysone, is accompanied by continuous growth of granule diameter with concomitant reduction in their number per cell [13].
  • Two domains found in the D. melanogaster P transposase (helix-turn-helix and leucine zipper) are well conserved in the putative proteins encoded by PS2 and PS18 [14].
  • Additionally, PS2 integrin can cause cell spreading on RGD peptide [15].

Regulatory relationships of if

  • Many mutations in the I-like domain reduce integrin expression specifically when betaPS is combined with activating alphaPS2 cytoplasmic mutations, indicating that integrins in the extended conformation are unstable relative to the inactive, bent heterodimers [16].

Other interactions of if


Analytical, diagnostic and therapeutic context of if


  1. Integrins: a role for adhesion molecules in olfactory memory. Connolly, J.B., Tully, T. Curr. Biol. (1998) [Pubmed]
  2. Developmentally regulated alternative splicing of Drosophila integrin PS2 alpha transcripts. Brown, N.H., King, D.L., Wilcox, M., Kafatos, F.C. Cell (1989) [Pubmed]
  3. The Drosophila PS2 antigen is an invertebrate integrin that, like the fibronectin receptor, becomes localized to muscle attachments. Bogaert, T., Brown, N., Wilcox, M. Cell (1987) [Pubmed]
  4. Requirement for integrins during Drosophila wing development. Brower, D.L., Jaffe, S.M. Nature (1989) [Pubmed]
  5. Specificity of PS integrin function during embryogenesis resides in the alpha subunit extracellular domain. Martin-Bermudo, M.D., Dunin-Borkowski, O.M., Brown, N.H. EMBO J. (1997) [Pubmed]
  6. PS2 integrin requirements in Drosophila embryo and wing morphogenesis. Brabant, M.C., Brower, D.L. Dev. Biol. (1993) [Pubmed]
  7. zipper Nonmuscle myosin-II functions downstream of PS2 integrin in Drosophila myogenesis and is necessary for myofibril formation. Bloor, J.W., Kiehart, D.P. Dev. Biol. (2001) [Pubmed]
  8. Disruption of C-terminal cytoplasmic domain of betaPS integrin subunit has dominant negative properties in developing Drosophila. Jannuzi, A.L., Bunch, T.A., Brabant, M.C., Miller, S.W., Mukai, L., Zavortink, M., Brower, D.L. Mol. Biol. Cell (2002) [Pubmed]
  9. Development of the indirect flight muscle attachment sites in Drosophila: role of the PS integrins and the stripe gene. Fernandes, J.J., Celniker, S.E., VijayRaghavan, K. Dev. Biol. (1996) [Pubmed]
  10. The PS2 integrin ligand tiggrin is required for proper muscle function in Drosophila. Bunch, T.A., Graner, M.W., Fessler, L.I., Fessler, J.H., Schneider, K.D., Kerschen, A., Choy, L.P., Burgess, B.W., Brower, D.L. Development (1998) [Pubmed]
  11. Migration of the Drosophila primordial midgut cells requires coordination of diverse PS integrin functions. Martin-Bermudo, M.D., Alvarez-Garcia, I., Brown, N.H. Development (1999) [Pubmed]
  12. Nonequivalent requirements for PS1 and PS2 integrin at cell attachments in Drosophila: genetic analysis of the alpha PS1 integrin subunit. Brower, D.L., Bunch, T.A., Mukai, L., Adamson, T.E., Wehrli, M., Lam, S., Friedlander, E., Roote, C.E., Zusman, S. Development (1995) [Pubmed]
  13. Developmental regulation of granule size and numbers in larval salivary glands of drosophila by steroid hormone ecdysone. Farkas, R., Suáková, G. Cell Biol. Int. (1999) [Pubmed]
  14. A P element of Scaptomyza pallida is active in Drosophila melanogaster. Simonelig, M., Anxolabéhère, D. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
  15. Drosophila PS2 integrin mediates RGD-dependent cell-matrix interactions. Bunch, T.A., Brower, D.L. Development (1992) [Pubmed]
  16. Identification of integrin beta subunit mutations that alter heterodimer function in situ. Jannuzi, A.L., Bunch, T.A., West, R.F., Brower, D.L. Mol. Biol. Cell (2004) [Pubmed]
  17. Drosophila PS1 integrin is a laminin receptor and differs in ligand specificity from PS2. Gotwals, P.J., Fessler, L.I., Wehrli, M., Hynes, R.O. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
  18. Genetic analysis on the role of integrin during axon guidance in Drosophila. Hoang, B., Chiba, A. J. Neurosci. (1998) [Pubmed]
  19. The localized assembly of extracellular matrix integrin ligands requires cell-cell contact. Martin-Bermudo, M.D., Brown, N.H. J. Cell. Sci. (2000) [Pubmed]
  20. Functions for PS integrins in tissue adhesion, migration, and shape changes during early embryonic development in Drosophila. Roote, C.E., Zusman, S. Dev. Biol. (1995) [Pubmed]
  21. Tiggrin, a novel Drosophila extracellular matrix protein that functions as a ligand for Drosophila alpha PS2 beta PS integrins. Fogerty, F.J., Fessler, L.I., Bunch, T.A., Yaron, Y., Parker, C.G., Nelson, R.E., Brower, D.L., Gullberg, D., Fessler, J.H. Development (1994) [Pubmed]
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