A gene residing at 47.9 on the genetic map and within segment 84B of the salivary map of Drosophila melanogaster. The Antp gene is one of a cluster of three genes that specify the type of differentiation that cells in the segments from the head to the anterior portion of the second thoracic segment will undergo. Mutations in the Antp gene cause the transformation of the segment that normally produces the antenna into one that produces a middle leg. The gene encodes a protein characterized by a homeobox (q.v.). This is a segment of 60 amino acids that lies close to the C terminus of the Antp protein. The amino acid sequence of this segment is shown above. It binds to target DNA sequences by its helix-turn-helix motif (q.v.). The complete three-dimensional structures of the Antp homeodomain as well as of the homeodomain-target DNA complex have been determined using NMR spectroscopy (q.v.) and x-ray crystallography (q.v.). See Chronology, 1983, Scott et al.; 1989, Qian et al.; 1990, Maliki, Schughart, and McGinnis; bithorax, homeotic mutations, Hox genes, Polycomb, proboscipedia, segment identity genes.
Subjects: Genetics and Genomics.