The antennapedia homeodomain is a sequence-specific transcription factor from the organism Drosophila melanogaster. This protein is encoded by the Antennapedia (antp) gene. However, the antennapedia homeodomain (Antp) shown here is a mutant. Cys39 has been changed to a Serine residue (C39-->S). Antp is a member of a regulatory system that gives cells specific positions on the anterior-posterior axis of the organism. Thus, Antp aids in the control of cell development in the mesothorax segment in Drosophila.
The homeobox domain, or homeodomain, is one that binds DNA through a helix-turn-helix structural motif. Proteins that contain a homeobox domain usually play a role in development, and many of these are sequence-specific transcription factors such as Antp.
The antennapedia homeodomain is 68 amino acid residues long. It contains four alpha helices: Helix 1 (res.10-21)=Red, helix 2 (res.28-38)=Yellow, helix 3 (res.42-52)=Green, and helix 4 (res.53-59)=Blue. Helices 2 and 3 adopt a helix-turn-helix motif from residues 28 to 52. This motif is similar to those found in prokaryotic repressor proteins.

• Keywords: Homeobox, DNA-Binding, Developemental Protein, Nuclear Protein
• View this protein's PDB entry as 2HOA
• View this protein's SwissProt entry as HMAN_DROME
• References:
  • P. Guntert, Y. -Q. Qian, G. Otting, M. Muller, W.J. Gehring, K. Wuthrich
    Structure Determination of the ANTP (C39->S) Homeodomain From Nuclear Magnetic Resonance Data in Solution Using a Novel Strategy for the Structure Calculation With the Programs DIANA, CALIBA, HABAS, and GLOMSA.
    J. Mol. Biol. 217:531 (1991)
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  • Y. -Q. Qian, M. Billeter, G. Otting, M. Mueller, W. J. Gehring, K. Wuthrich
    The Structure of the Antennapedia Homeodomain Determined by NMR Spectroscopy in Solution: Comparison With Prokaryotic Repressors.
    Cell 59:573 (1989)
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  • M. Billeter, Y. -Q. Qian, G. Otting, M. Mueller, W. J. Gehring, K. Wuthrich
    Determination of the Three-Dimensional Structure of the Antennapedia Homeodomain From Drosophila in Solution by 1H Nuclear Magnetic Resonance Spectroscopy.
    J. Mol. Biol. 214:183 (1990)
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  • G. Otting, Y. -Q. Qian, M. Mueller, M. Affolter, W. J. Gehring, K. Wuthrich
    Secondary Structure Determination for the ntennapedia Homeodomain by Nuclear Magnetic Resonance and Evidence for a Helix-Turn-Helix Motif.
    EMBO 7:4305 (1988)
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