This 14 amino acid motif has been identified within the C-terminal region of several Paired-like homeodomain (HD) (see <PDOC00027>) containing proteins [1,2]. It was named OAR domain after the initials of otp, aristaless, and rax [3].

Although it has been proposed that this domain could be important for transactivation and be involved in protein-protein interactions or DNA binding [3,4], its function is not yet known.

Some proteins known to contain an OAR domain are listed below:

• Human RIEG. Defects in this protein are the cause of Rieger syndrome, an autosomal dominant disorder that includes anomalies of the anterior chamber of the eye, dental hypoplasia and a protuberant umbilicus [1].
• Mammalian OG12X. The function of these proteins is not yet known [2].
• Vertebrate Rax, encoded by the retina and anterior neural fold homeobox gene. This protein plays a role in the proliferation and/or differentiation of retinal cell [3].
• Drosophila DRX. It could be a homolog of vertebrate Rax. It appears to be important in brain development [5].
• Human SHOX, encoded by the short stature homeobox-containing gene. Defects or lack of this protein are the cause of short stature associated with the Turner syndrome [4].
• Mammalian PITX3. This protein appears to be involved in normal eye anterior-chamber and lens development [6,7]. In human, defects in PITX3 are associated with anterior segment mesenchymal dysgenesis (ASMD) and autosomal-dominant congenital cataracts (ADCC) [7].
• Vertebrate Pax3 and Pax7, transcription factors that play fundamental roles in the development of multi-cellular animals (Metazoa) [8].
• Vertebrate visual system homeobox 2 (VSX2) [8].
• Vertebrate dorsal root ganglia homeobox protein (DRG11) [8].

The OAR domain has also been called paired-type homeodomain tail (PHT), paired tail or C-peptide domain [8].

The profile we developed covers the entire OAR domain.