TBP

TBP, or TATA-binding protein, is a universal transcription factor essential for initiation of transcription by RNA polymerase II in eukaryotes. It recognizes the TATA box in many promoters, binds the DNA minor groove, and bends the DNA sharply. This bending promotes assembly of the pre-initiation complex by facilitating recruitment of TBP-associated factors and other general transcription factors, enabling RNA polymerase II transcription. TBP also participates in transcription by RNA polymerase I and III as part of related complexes (SL1 for Pol I and TFIIIB for Pol III).

TBP comprises a conserved C-terminal core that forms a saddle-shaped structure binding the DNA minor groove and inducing the bend; the N-terminal region is variable and regulatory in eukaryotes, contributing to interactions with TBP-associated factors in TFIID. Archaea have an analogous TBP, typically lacking a long N-terminal extension.

TBP is a component of the TFIID complex, but metazoans also express TBP-related factors (TRF1, TRF2, TRF3) that can direct transcription at specific promoters. TBP function is modulated by transcription activators, chromatin modifiers, and post-translational modifications, enabling promoter selectivity and context-dependent transcription.

Clinical notes: In humans, expansions of CAG repeats in the TBP gene cause spinocerebellar ataxia type 17 (SCA17); other TBP variants may influence disease risk by altering transcription initiation. Beyond disease, TBP remains a central hub in transcriptional regulation due to its pivotal role in promoter recognition.

TBP is most commonly the TATA-binding protein in molecular biology, though the acronym has other meanings in different fields.