The TBP gene encodes TATA Box-Binding Protein, the DNA-binding subunit of the RNA polymerase II transcription factor D (TFIID). As the name suggests, the TBP subunit attaches to the DNA promoter at its TATA box, to initiate transcription. Binding of the TFIID complex at the promoter helps in positioning of RNA Polymerase II and serves as a scaffold for the assembly of other polypeptides to the transcription complex. It also acts as a channel for regulatory signals.
Mutations in the TBP gene have been associated with Spinocerebellar Ataxia 17 (SCA17), a progressive neurodegenerative disorder characterised by gait and limb ataxia, intention tremors, cerebellar atrophy and behavioural manifestations such as psychosis, disorientation and aggression. The gene has also been associated with an increased susceptibility to Late-Onset Parkinson Disease.