Final answer:
The TATA binding protein (TBP) binds to the TATA box sequence in eukaryotic promoters and provides access to the DNA strand for transcriptional initiation.
Step-by-step explanation:
The function of the TATA binding protein (TBP) in transcriptional initiation is to provide access to the DNA strand to be transcribed.
TFIID, which contains TBP, first binds to the TATA box sequence in the core promoter region. Binding of TFIID recruits other transcription factors, such as TFIIB, TFIIE, TFIIF, and TFIIH, to form the transcription initiation complex.
This complex helps to bind the RNA polymerase to the promoter and activate transcription. Once the complex is assembled, RNA polymerase binds to the upstream sequence, becomes phosphorylated, and starts transcription.