For transcribing protein coding genes, the RNA Polymerase forms the preinitiation complex
(PIC) in association with:
A.TFIIA, TFIID, TFIIG
B. TFIIA, TFIIG, TFIIH
C.TFIIH, TFIIF, TFIID
D.TFIIC, TFIID, TFIIF

RNA Polymerase II and the Preinitiation Complex: What’s the Right Combination?

Introduction

Transcription of protein-coding genes in eukaryotes is a well-coordinated event involving multiple transcription factors and RNA Polymerase II. A crucial step in this process is the formation of the Preinitiation Complex (PIC) at the core promoter region.

Question: For transcribing protein-coding genes, the RNA Polymerase forms the Preinitiation Complex (PIC) in association with:

• A. TFIIA, TFIID, TFIIG
• B. TFIIA, TFIIG, TFIIH
• C. TFIIH, TFIIF, TFIID
• D. TFIIC, TFIID, TFIIF

Let’s dive into the components of the PIC to find the correct answer.

Understanding the Preinitiation Complex (PIC)

The PIC is formed at the TATA box of a promoter and is essential for transcription initiation. It includes:

• RNA Polymerase II
• General transcription factors (GTFs): TFIID, TFIIA, TFIIB, TFIIF, TFIIE, and TFIIH

Among these, the most critical ones involved in early assembly of the PIC are:

• TFIID: Recognizes and binds to the TATA box
• TFIIF: Stabilizes the interaction between RNA Pol II and TFIIB
• TFIIH: Has helicase activity to unwind DNA and kinase activity to phosphorylate the CTD of RNA Pol II

Correct Answer:

✅ Option C. TFIIH, TFIIF, TFIID

Why Not the Others?

• TFIIG: Not a recognized general transcription factor in this context
• TFIIC: Involved in RNA Polymerase III transcription, not Pol II

Conclusion

The formation of the Preinitiation Complex (PIC) is a vital step in the transcription of protein-coding genes by RNA Polymerase II. The correct combination of transcription factors that associate with it includes:

• TFIID: Binds promoter
• TFIIF: Binds RNA Pol II
• TFIIH: Unwinds DNA and phosphorylates RNA Pol II

Mastering these associations is essential for understanding gene regulation and expression.

Key Phrase:

RNA polymerase preinitiation complex transcription factors