1oa8
AXH domain of human spinocerebellar ataxin-1
Structural highlights
DiseaseATX1_HUMAN Spinocerebellar ataxia type 1. Defects in ATXN1 are the cause of spinocerebellar ataxia type 1 (SCA1) [MIM:164400; also known as olivopontocerebellar atrophy I (OPCA I or OPCA1). Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to cerebellum degeneration with variable involvement of the brainstem and spinal cord. SCA1 belongs to the autosomal dominant cerebellar ataxias type I (ADCA I) which are characterized by cerebellar ataxia in combination with additional clinical features like optic atrophy, ophthalmoplegia, bulbar and extrapyramidal signs, peripheral neuropathy and dementia. SCA1 is caused by expansion of a CAG repeat in the coding region of ATXN1. Longer expansions result in earlier onset and more severe clinical manifestations of the disease.[1] [2] FunctionATX1_HUMAN Chromatin-binding factor that repress Notch signaling in the absence of Notch intracellular domain by acting as a CBF1 corepressor. Binds to the HEY promoter and might assist, along with NCOR2, RBPJ-mediated repression. Binds RNA in vitro. May be involved in RNA metabolism. The expansion of the polyglutamine tract may alter this function.[3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSpinocerebellar ataxia type 1 is a late-onset neurodegenerative disease caused by the expansion of a CAG triplet repeat in the SCA1 gene. This results in the lengthening of a polyglutamine tract in the gene product ataxin-1. This produces a toxic gain of function that results in specific neuronal death. A region in ataxin-1, the AXH domain, exhibits significant sequence similarity to the transcription factor HBP1. This region of the protein has been implicated in RNA binding and self-association. We have determined the crystal structure of the AXH domain of ataxin-1. The AXH domain is dimeric and contains an OB-fold, a structural motif found in many oligonucleotide-binding proteins, supporting its proposed role in RNA binding. By structure comparison with other proteins that contain an OB-fold, a putative RNA-binding site has been identified. We also identified a cluster of charged surface residues that are well conserved among AXH domains. These residues may constitute a second ligand-binding surface, suggesting that all AXH domains interact with a common yet unidentified partner. The structure of the AXH domain of spinocerebellar ataxin-1.,Chen YW, Allen MD, Veprintsev DB, Lowe J, Bycroft M J Biol Chem. 2004 Jan 30;279(5):3758-65. Epub 2003 Oct 28. PMID:14583607[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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