Which transcription factor is known to be involved in promoter melting?

The involvement of TF2H in promoter melting is significant because this transcription factor possesses DNA helicase activity, which is critical for unwinding the DNA strands during the initiation of transcription. Promoter melting refers to the process where the DNA double helix is separated at the promoter region to allow RNA polymerase access to the template strand for transcription to begin. TF2H is essential in stabilizing this unwound region of DNA and facilitating the transition from a closed complex to an open complex, which is necessary for the subsequent stages of transcription.

In contrast, while other transcription factors like TF2D, TF2B, and TF2A are also involved in the initiation of transcription, they do not directly participate in the physical process of melting the DNA strands. TF2D primarily helps in recognizing the promoter and recruiting the transcription machinery, TF2B assists RNA polymerase to bind to the promoter, and TF2A may enhance the stability of the pre-initiation complex but lacks helicase activity critical for promoter melting. Thus, TF2H stands out as the key player in this specific step of transcription initiation.