Which transcription factor links RNAP2 to TBP?

The correct choice identifies TF2D as the transcription factor that links RNA polymerase II (RNAP2) to the TATA-binding protein (TBP). TF2D is a crucial component of the transcription initiation complex for protein-coding genes transcribed by RNAP2.

TF2D is a multi-subunit complex that contains TBP as well as a number of TBP-associated factors (TAFs). The primary role of TF2D is to recognize the promoter region of the gene through the binding of TBP to the TATA box. This interaction is essential for the assembly of the transcription machinery. After TF2D is bound to the promoter, it serves as a platform for the recruitment of other general transcription factors, including TF2B, which is involved in providing an interface for RNAP2 to start transcription.

This function of TF2D highlights its importance in the initiation of transcription. Its ability to link TBP with RNAP2 ensures that the RNA polymerase machinery is correctly positioned at the promoter to begin RNA synthesis.