Disease:Defects in TBP are the cause of spinocerebellar ataxia type 17 (SCA17) [MIM:607136]. 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 degeneration of the cerebellum with variable involvement of the brainstem and spinal cord. SCA17 is an autosomal dominant cerebellar ataxia (ADCA) characterized by widespread cerebral and cerebellar atrophy, dementia and extrapyramidal signs. The molecular defect in SCA17 is the expansion of a CAG repeat in the coding region of TBP. Longer expansions result in earlier onset and more severe clinical manifestations of the disease.,Function:General transcription factor that functions at the core of the DNA-binding multiprotein factor TFIID. Binding of TFIID to the TATA box is the initial transcriptional step of the pre-initiation complex (PIC), playing a role in the activation of eukaryotic genes transcribed by RNA polymerase II.,polymorphism:The poly-Gln region of TBP is highly polymorphic (25 to 42 repeats) in normal individuals and is expanded to about 47-63 repeats in spinocerebellar ataxia 17 (SCA17) patients.,similarity:Belongs to the TBP family.,subunit:Belongs to the TFIID complex together with the TBP-associated factors (TAFs). Component of the transcription factor SL1/TIFIB complex, composed of TBP and at least TAF1A, TAF1B TAF1C, and TAF3. Binds DNA as monomer. Interacts with TAFs, TFIIB, NCOA6, DRAP1, DR1 and ELF3. Interacts with SPIB, SNAPC1, SNAPC2 and SNAPC4. Interacts with HIV-1 Tat. Interacts with UTF1 which acts as a coactivator of ATF2 transcriptional activity. Interacts with GPBP1 (By similarity). Interacts with BRF2.,tissue specificity:Widely expressed, with levels highest in the testis and ovary.,
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