A comprehensive classification of homeobox genes

Abstract

Abstract The homeodomain was originally described as a highly conserved protein motif of 60 to 63 amino acids, encoded by a short DNA fragment, the horneobox, that was found in Drosophila developmental control genes (McGinnis et al., 1984; Scott and Weiner, 1984). As more and more homeobox-containing genes were isolated it became obvious that for closely related homeodomains the sequence similarity could be extended upstream and/or downstream of the core 60 amino acids (for a previous compilation, see Scott et al., 1989). In contrast, highly divergent homeodomain sequences have been identified for which the sequence similarity is shorter than the orig inally defined 60 amino acids. The definition of the homeodomain used here is based on the canonical 60 amino acid core as it is most often used.