Question

Which of the following statements is NOT true for eukaryotic transcription?

• A. Core promoter determines the location of start point
• B. Transcription factors recognize the promoter
• C. Transcription factors are cis-regulatory proteins
• D. Transcription termination is different for different RNA polymerases

Answer 1

The correct option is C Transcription factors are cis-regulatory proteins

The transcription factors are trans-acting which means they are produced by genes away from the DNA sequence they affect. In eukaryotic transcription, many transcription factors are required for many different functions. One of them is recognition of the promoter to which RNA polymerase binds and initiates transcription. For transcription termination, all three polymerases use different strategies.
A cis-acting sequence that regulates the expression of a gene is located on the same chromosome.

In eukaryotes, transcription termination is different for different RNA polymerase

• RNA polymerase I transcription termination is similar to rho-dependant termination in prokaryotes. The ribosomal rRNA genes transcribed by RNA Polymerase I contain a specific sequence of base pairs that is recognized by a termination protein called TTF-1.
• The protein-encoding, structural RNA, and regulatory RNA genes transcribed by RNA Polymerase II lack any specific signals or sequences that direct RNA Polymerase II to terminate at specific locations. The transcript is cleaved at an internal site before RNA Polymerase II finishes transcribing, while RNA Polymerase II can continue to transcribe RNA.
• RNA polymerase-III transcription termination is similar to rho-independent termination in prokaryotes. The genes transcribed by RNA Polymerase III have a short stretch of four to seven U’s at their 3′ end. This somehow triggers RNA Polymerase III to both release the nascent RNA and disengage from the template DNA strand.