RAX is a transcription factor that plays a critical role in the eye and forebrain development of vertebrate species. It is involved in the establishment of the retina []. Mutations in the RAX gene cause microphthalmia, isolated 3, which is a disorder of eye formation, ranging from small size of a single eye to complete bilateral absence of ocular tissues [].Retina and anterior neural fold homeobox protein 2 (RAX2) is known to bind to the Ret-1 and Bat-1 element within the rhodopsin promoter and may be involved in modulating the expression of photoreceptor specific genes [].This entry includes a group of homeobox proteins, including RAX and RAX2.
This 14 amino acid motif has been identified within the C-terminal region of several paired-like homeodomain (HD) containing proteins [, ]. It was named OAR domain after the initials of otp, aristaless, and rax []. Although it has been proposed that this domain could be important for transactivation and be involved in protein-protein interactions or DNA binding [, ], its function is not yet known. Some proteins known to contain a OAR domain include human RIEG, defects in which are the cause of Rieger syndrome []; human OG12X and Mus musculus (Mouse) Og12x, whose function is not yet known []; vertebrate Rax, which plays a role in the proliferation and/or differentiation of retinal cells []; Drosophila DRX, which appears to be important in brain development []; and human SHOX, encoded by the short stature homeobox-containing gene.
