The TFIID basal transcription factor complex plays a major role in the initiation of RNA polymerase II (Pol II)-dependent transcription (PubMed:33795473). TFIID recognizes and binds promoters with or without a TATA box via its subunit TBP, a TATA-box-binding protein, and promotes assembly of the pre-initiation complex (PIC) (PubMed:33795473, PubMed:27193682, PubMed:2194289, PubMed:2363050, PubMed:2374612). The TFIID complex consists of TBP and TBP-associated factors (TAFs), including TAF1, TAF2, TAF3, TAF4, TAF5, TAF6, TAF7, TAF8, TAF9, TAF10, TAF11, TAF12 and TAF13 (PubMed:33795473, PubMed:27007846). The TFIID complex structure can be divided into 3 modules TFIID-A, TFIID-B, and TFIID-C (PubMed:33795473). TBP forms the TFIID-A module together with TAF3 and TAF5 (PubMed:33795473). TBP is a general transcription factor that functions at the core of the TFIID complex (PubMed:33795473, PubMed:27193682, PubMed:2194289, PubMed:2363050, PubMed:2374612, PubMed:9836642). During assembly of the core PIC on the promoter, as part of TFIID, TBP binds to and also bends promoter DNA, irrespective of whether the promoter contains a TATA box (PubMed:33795473). Component of a BRF2-containing transcription factor complex that regulates transcription mediated by RNA polymerase III (PubMed:26638071). Component of the transcription factor SL1/TIF-IB complex, which is involved in the assembly of the PIC during RNA polymerase I-dependent transcription (PubMed:15970593). The rate of PIC formation probably is primarily dependent on the rate of association of SL1 with the rDNA promoter (PubMed:15970593). SL1 is involved in stabilization of nucleolar transcription factor 1/UBTF on rDNA (PubMed:15970593). Binds DNA as monomer (PubMed:2194289, PubMed:2374612). Component of the TFIID basal transcription factor complex, composed of TATA-box-binding protein TBP, and a number of TBP-associated factors (TAFs), including TAF1, TAF2, TAF3, TAF4, TAF5, TAF6, TAF7, TAF8, TAF9, TAF10, TAF11, TAF12 and TAF13 (PubMed:9836642, PubMed:27007846, PubMed:33795473). Part of a TFIID-containing RNA polymerase II pre-initiation complex that is composed of TBP and at least GTF2A1, GTF2A2, GTF2E1, GTF2E2, GTF2F1, GTF2H2, GTF2H3, GTF2H4, GTF2H5, GTF2B, TCEA1, ERCC2, ERCC3, TAF1, TAF2, TAF3, TAF4, TAF5, TAF6, TAF7, TAF8, TAF9, TAF10, TAF11, TAF12 and TAF13 (PubMed:27007846, PubMed:33795473). Component of the transcription factor SL1/TIF-IB complex, composed of TBP and at least TAF1A, TAF1B, TAF1C and TAF1D (PubMed:7801123). Association of TBP to form either TFIID or SL1/TIF-IB appears to be mutually exclusive (PubMed:7801123). Interacts with TAF1A, TAF1B and TAF1C (PubMed:7801123). Interacts with TFIIB, NCOA6, DRAP1, DR1 and ELF3 (PubMed:11461703, PubMed:10391676, PubMed:10567404). Interacts with SPIB, SNAPC1, SNAPC2 and SNAPC4 (PubMed:12621023, PubMed:10196196). Interacts with UTF1 (PubMed:9748258). Interacts with BRF2; this interaction promotes recruitment of BRF2 to TATA box-containing promoters (PubMed:11564744, PubMed:26638071). Interacts with UBTFD (PubMed:7982918). Interacts with GPBP1D (By similarity). Interacts with CITED2 (By similarity). Interacts with ATF7IP (Probable). Interacts with LLPH (By similarity). Interacts with HSF1 (via transactivation domain) (PubMed:11005381). Interacts with GTF2B (via C-terminus); this interaction with promoter-bound TBP guides RNA polymerase II into the pre-initiation complex (PIC) (PubMed:8504927). Interacts with PAX5 (PubMed:10197586). (Microbial infection) Interacts with HIV-1 Tat. (Microbial infection) Interacts with herpes simplex virus 1 ICP4. (Microbial infection) Interacts with herpes simplex virus 2 ICP4. (Microbial infection) Interacts with human adenovirus E1A protein; this interaction probably disrupts the TBP-TATA complex. Widely expressed, with levels highest in the testis and ovary. 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. The disease is caused by variants affecting the gene represented in this entry. Belongs to the TBP family.