title: Structure, upstream promoter region, and functional domains of a mouse and human Mix paired-like homeobox gene.
abstract: Mix/Bix proteins represent a vertebrate subgroup of paired-like homeodomain proteins which are known to function around the time of gastrulation. Here we report the structures of the genomic and upstream promoter regions of a mouse and human Mix-like gene. Both genes map to syntenic regions of chromosome 1 and contain two coding exons, with the paired-type homeodomain split between the exons within helix 3. Differentiating mouse embryonic stem cells transcribe a messenger RNA of approximately 2.6 kb. The first exon encodes the translation initiation codon and a 5' untranslated region of approximately 90 bp. Sequence analysis of the 960 bp upstream of the transcription start site of the mouse Mix gene revealed the presence of a putative initiator region and TATA box as well as potential Smad, FoxH1/FAST, T-box, COUP-TF, C/EBP, GATA, HNF3 binding sites and retinoic acid response elements. A number of these sites are conserved in the human Mix promoter. We find that most paired-related homeodomain proteins, including mouse and human Mix, contain a proline-rich region within their amino termini which may interact with other proteins. Mouse and human Mix proteins contain highly conserved carboxy-terminal polar/acidic regions with the potential to form an amphipathic helix and the ability to activate transcription in yeast. Mouse Mix expressed in COS cells or in vitro binds a DNA consensus sequence identified previously for paired class homeodomain proteins. These studies suggest that a number of features of paired-like protein structure and function are conserved across diverse species and provide a useful framework for studying the function and regulation of the mouse Mix gene.
authors.affiliation: Department of Medicine, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Sahr
authors.forename: Dora Campos
authors.initials: DC
authors.lastname: Dias
authors.forename: Roberto
authors.initials: R
authors.lastname: Sanchez
authors.forename: Dongli
authors.initials: D
authors.lastname: Chen
authors.forename: Siming W
authors.initials: SW
authors.lastname: Chen
authors.forename: Lorraine J
authors.initials: LJ
authors.lastname: Gudas
authors.forename: Margaret H
authors.initials: MH
authors.lastname: Baron
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D002460:Cell Line; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005796:Genes / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D020014:K562 Cells; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D026801:Synteny; D024363:Transcription Initiation Site
chemical_list: D018076:DNA, Complementary; D018398:Homeodomain Proteins; C499230:MIXL1 protein, human; C464781:Mixl1 protein, mouse; D009841:Oligonucleotides; D004247:DNA