Regulation of Hox activity: insights from protein motifs.

Deciphering the molecular bases of animal body plan construction is a central question in developmental and evolutionary biology. Genome analyses of a number of metazoans indicate that widely conserved regulatory molecules underlie the amazing diversity of animal body plans, suggesting that these molecules are reiteratively used for multiple purposes. Hox proteins constitute a good example of such molecules and provide the framework to address the mechanisms underlying transcriptional specificity and diversity in development and evolution. Here we examine the current knowledge of the molecular bases of Hox-mediated transcriptional control, focusing on how this control is encoded within protein sequences and structures. The survey suggests that the homeodomain is part of an extended multifunctional unit coordinating DNA binding and activity regulation and highlights the need for further advances in our understanding of Hox protein activity.