title: Origins and evolvability of the PAX family.
abstract: The paired box (PAX) family of transcription/developmental genes plays a key role in numerous stages of embryonic development, as well as in adult organogenesis. There is evidence linking the acquisition of a paired-like DNA binding domain (PD) to domestication of a Tc1/mariner transposon. Further duplication/deletion processes led to at least five paralogous metazoan protein groups, which can be classified into two supergroups, PAXB-like or PAXD-like, using ancestral defining structures; the PD plus an octapeptide motif (OP) and a paired-type homeobox DNA binding domain (PTHD), producing the PD-OP-PTHD structure characteristic of the PAXB-like group, whereas an additional domain, the paired-type homeodomain tail (PHT), is present in the PAXD-like group, producing a PD-OP-PTHD-PHT structure. We examined their patterns of distribution in various species, using both available data and new bioinformatic analyses, including vertebrate PAX genes and their shared and specific functions, as well as inter- and intraspecific variability of PAX in primates. These analyses revealed a relatively conserved PAX network, accompanied by specific changes that led to adaptive novelties. Therefore, both stability and evolvability shaped the molecular evolution of this key transcriptional network.
authors: Department of Biology, Biology Institute, Federal University of Bahia, Salvador, BA, Brazil. Electronic address: vanessa.cortes@ufba.br.
authors: Vanessa R
authors: VR
authors: Paixão-Côrtes
authors: Department of Genetics, Biosciences Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: francisco.salzano@ufrgs.br.
authors: Francisco M
authors: FM
authors: Salzano
authors: Department of Genetics, Biosciences Institute, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address: maria.bortolini@ufrgs.br.
authors: Maria Cátira
authors: MC
authors: Bortolini
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D051761:Paired Box Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D051761:Paired Box Transcription Factors
keywords: Metazoan PAX evolution; PAX transcriptional family; Paired box proteins; Primate PAX variability; Tc1/mariner transposons; Vertebrate PAX functions