Homeodomain Fold - Homeobox Genes

Homeobox Genes

The homeobox is a stretch of DNA about 180 nucleotides long that encodes a homeodomain. Homeobox genes code for homeodomain proteins in both vertebrates and invertebrates. The existence of homeoboxes was first discovered in Drosophila, where the radical alterations that resulted from mutations in homeobox genes were termed homeotic mutations. The most famous such mutation is Antennapedia, in which legs grow from the head of a fly instead of the expected antennae. Homeobox genes are critical in the establishment of body axes during embryogenesis.

The consensus 60-polypeptide chain is (typical intron position noted with dashes)

RRRKRTA-YTRYQLLE-LEKEFLF-NRYLTRRRRIELAHSL-NLTERHIKIWFQN-RRMK-WKKEN

The motif is highly conserved over hundreds of millions of years of evolutionary history, with typically 80% match in the corresponding nucleotide sequence to the consensus sequence across species, genera and phyla.