Authors: Eugene Vorobyov Jürgen Horst
Publish Date: 2006/07/07
Volume: 63, Issue: 2, Pages: 153-164
Abstract
Pax genes encode transcription factors governing the determination of different cell types and even organs in the development of multicellular animals Pax proteins are characterized by the presence of three evolutionarily conserved elements two DNAbinding domains the paired domain PD and pairedtype homeodomain PtHD and the short octopeptide sequence OP located between PD and PtHD PD is the defining feature of this class of genes while OP and/or PtHD may be divergent or absent in some members of the family Phylogenetic analyses of the PD and PtHD sequences do not distinguish which particular type of the extant Pax genes more resembles the ancestral type Here we present evidence for the existence of a fourth evolutionarily conserved domain in the Pax proteins the pairedtype homeodomain tail PHT Our data also imply that the hypothetical protoPax protein most probably exhibited a complex structure PDOPPtHDPHT which has been retained in the extant proteins Pax3/7 of the ascidia and lancelet and Pax7 of the vertebrates Finally based on structural considerations a scenario for the evolutionary emergence of the protoPax gene is proposedWe are grateful to CE Cook and J Schmitz for critical reading of the manuscript valuable comments and helpful discussions We also thank A Perevozchikov and A Karabinos for providing the Amphioxus genomic DNA This study was supported by the Deutsche Forschungsgemeinschaft EV dedicates this paper to I Vorobyova
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