title: Six class homeobox genes in drosophila belong to three distinct families and are involved in head development.
abstract: The vertebrate Six genes are homologues of the Drosophila homeobox gene sine oculis (so), which is essential for development of the entire visual system. Here we describe two new Six genes in Drosophila, D-Six3 and D-Six4, which encode proteins with strongest similarity to vertebrate Six3 and Six4, respectively. In addition, we report the partial sequences of 12 Six gene homologues from several lower vertebrates and show that the class of Six proteins can be subdivided into three major families, each including one Drosophila member. Similar to so, both D-Six3 and D-Six4 are initially expressed at the blastoderm stage in narrow regions of the prospective head and during later stages in specific groups of head midline neurectodermal cells. D-Six3 may also be essential for development of the clypeolabrum and several head sensory organs. Thus, the major function of the ancestral Six gene probably involved specification of neural structures in the cephalic region.
authors.affiliation: Department of Molecular Biology, University of Bergen, HIB-Biobuilding, N-5020, Bergen, Norway.
authors.forename: H C
authors.initials: HC
authors.lastname: Seo
authors.forename: J
authors.initials: J
authors.lastname: Curtiss
authors.forename: M
authors.initials: M
authors.lastname: Mlodzik
authors.forename: A
authors.initials: A
authors.lastname: Fjose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila / Q000196:embryology* / Q000235:genetics*; D029721:Drosophila Proteins; D004622:Embryo, Mammalian / Q000033:anatomy & histology; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology; D005136:Eye Proteins / Q000032:analysis / Q000235:genetics; D005801:Genes, Homeobox; D006257:Head / Q000196:embryology*; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009024:Morphogenesis; D005810:Multigene Family; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D015534:Trans-Activators; D015027:Zebrafish / Q000235:genetics; D029961:Zebrafish Proteins; D000097607:Homeobox Protein SIX3
chemical_list: D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D015534:Trans-Activators; D029961:Zebrafish Proteins; D000097607:Homeobox Protein SIX3; C098490:Six4 protein, mouse; C087345:So protein, Drosophila; C484763:six2 protein, zebrafish; C490853:six4b protein, zebrafish; C490856:six5 protein, zebrafish