Eukaryotic RNA Polymerases and Assembly

Eukaryotic RNA Polymerases

• RNA Polymerase I synthesizes pre-ribosomal RNA, which serves as a precursor for 28S, 18S, and 5.8 rRNAs.
• RNA Polymerase II is responsible for the synthesis of mRNA.
• RNA Polymerase III produces tRNAs and some small RNA products.

RNA Polymerase Assembly

• Assembly of RNA Polymerase is initiated by the interaction of TATA-binding protein (TBP) with the promoter.
• Two transcription factors (IIA and IIB) bind to the promoter after TBP.
• Finally, TFIIE and TFIIH bind to the promoter, with TFIIE involved in DNA melting and TFIIH possessing helicase activity to unwind DNA.

Elongation, Termination, and Release

• TFIIF remains attached to RNA Polymerase II during elongation.
• Elongation factors help increase efficiency and prevent pausing.
• They also regulate post-transcriptional processing.
• At termination, the phosphate is removed from the RNA chain.

RNA Strand Initiation and Promoter Clearance

• The kinase activity in TFIIH phosphorylates RNA Polymerase, allowing it to escape the promoter.
• Initially, 60-70 RNA nucleotides are synthesized.
• Then, TFIIE and TFIIH are released, and the process moves to elongation.

This quiz covers the different types of RNA polymerases in eukaryotes, including RNA Polymerase I, II, and III, and their functions. It also explores the assembly of RNA polymerase, including the role of TATA-binding protein and other transcription factors.