InterPro domain: IPR005018

The DOMON domain is an 110-125 residue long domain which has been identifiedin the physiologically important enzyme dopamine beta-monooxygenase and inseveral other secreted and transmembrane proteins from both plants andanimals. It has been named after DOpamine beta-MOnooxygenase N-terminaldomain. The DOMON domain can be found in one to four copies and in associationwith other domains, such as the Cu-ascorbate dependent monooxygenase domain,the epidermal growth factor domain, the trypsin inhibitor-like domain (TIL), the SEA domain and the Reelin domain [ 1 ]. The DOMON domain may be involved in heme and sugar recognition [ 2 ].

The sequence conservation is predominantly centred around patches ofhydrophobic residues. The secondary structure prediction of the DOMON domainpoints to an all-beta-strand fold with seven or eight core strands supportedby a buried core of conserved hydrophobic residues. There is a chraracteristicmotif with two small positions (Gly or Ser) corresponding to a conserved turnimmediately C-terminal to strand three. It has been proposed that the DOMONdomain might form a beta-sandwich structure, with the strands distributed intotwo beta sheets as is seen in many extracellular adhesion domains such as theimmunoglobulin, fibronectin type III, cadherin and PKD domains [ 3 ].

1. DOMON: an ancient extracellular domain in dopamine beta-monooxygenase and other proteins. Trends Biochem. Sci. 26, 524-6
2. The DOMON domains are involved in heme and sugar recognition. Bioinformatics 23, 2660-4