SIX Homeobox 1 (SIX1) Human Recombinant Protein

The protein encoded by this gene is a homeobox protein that is similar to the Drosophila 'sine oculis' gene product. This gene is found in a cluster of related genes on chromosome 14 and is thought to be involved in limb development. Defects in this gene are a cause of autosomal dominant deafness type 23 (DFNA23) and branchiootic syndrome type 3 (BOS3). [provided by RefSeq, Jul 2008]

SIX1: May be involved in limb tendon and ligament development. Defects in SIX1 are the cause of deafness autosomal dominant type 23 (DFNA23). A form of non-syndromic deafness characterized by prelingual, bilateral, symmetric hearing loss with a conductive component present in some but not all patients. Defects in SIX1 are the cause of branchiootic syndrome type 3 (BOS3). BOS3 is a syndrome characterized by usually bilateral branchial cleft fistulas or cysts, sensorineural and/or conductive hearing loss, pre-auricular pits, and structural defects of the outer, middle or inner ear. Otic defects include malformed and hypoplastic pinnae, a narrowed external ear canal, bulbous internal auditory canal, stapes fixation, malformed and hypoplastic cochlea. Branchial and otic anomalies are as those seen in individuals with the branchiootorenal syndrome. However, renal anomalies are absent in branchiootic syndrome patients. Defects in SIX1 could be a cause of branchiootorenal syndrome (BOR). BOR is an autosomal dominant disorder manifested by various combinations of preauricular pits, branchial fistulae or cysts, lacrimal duct stenosis, hearing loss, structural defects of the outer, middle, or inner ear, and renal dysplasia. Associated defects include asthenic habitus, long narrow facies, constricted palate, deep overbite, and myopia. Hearing loss may be due to mondini type cochlear defect and stapes fixation. Penetrance of BOR syndrome is high, although expressivity can be extremely variable. Belongs to the SIX/Sine oculis homeobox family.

Protein type: Cell development/differentiation; DNA-binding; Transcription factor

Chromosomal Location of Human Ortholog: 14q23.1

Cellular Component: nucleoplasm; transcription factor complex; cytoplasm; nucleolus; nucleus

Molecular Function: protein binding; DNA binding; sequence-specific DNA binding; chromatin binding; transcription factor activity

Biological Process: regulation of neuron differentiation; apoptosis; positive regulation of transcription, DNA-dependent; middle ear morphogenesis; negative regulation of transcription from RNA polymerase II promoter; olfactory placode formation; regulation of epithelial cell proliferation; sensory perception of sound; regulation of protein localization; epithelial cell differentiation; regulation of transcription, DNA-dependent; ureteric bud development; induction of an organ; thyroid gland development; neuron fate specification; regulation of synaptic growth at neuromuscular junction; negative regulation of neuron apoptosis; kidney development; inner ear development; skeletal muscle development; inner ear morphogenesis; pharyngeal system development; transcription, DNA-dependent; thymus development; facial nerve morphogenesis; embryonic cranial skeleton morphogenesis; pattern specification process; embryonic skeletal morphogenesis; ureteric bud branching; generation of neurons; myoblast migration; positive regulation of transcription from RNA polymerase II promoter; regulation of satellite cell proliferation

Disease: Branchiootic Syndrome 3; Deafness, Autosomal Dominant 23; Branchiootorenal Syndrome 1