Which statement best describes the difference between general transcription factors and locus-specific transcription factors?

Which statement best describes the difference between general transcription factors and locus-specific transcription factors?

• A. General transcription factors are required for transcription of any gene by helping RNA Pol II bind promoters.
• B. Locus-specific transcription factors recruit RNA polymerase II directly to promoters regardless of enhancers.
• C. General transcription factors regulate expression of specific genes by binding enhancers.
• D. Locus-specific transcription factors are required for transcription of any gene by binding promoters.

Answer: (A)

The key idea is how transcription is initiated by different players: general transcription factors are part of the basal machinery, while locus-specific transcription factors provide gene- and context-specific regulation. General transcription factors are required for transcription initiation by RNA polymerase II at nearly all genes. They assemble at the core promoter to form the pre-initiation complex and help RNA Pol II recognize and bind the promoter, enabling transcription to start. This makes them essential for transcription across the genome, not just for a subset of genes. Locus-specific transcription factors, on the other hand, bind to DNA elements such as enhancers or specific promoter sequences to modulate transcription in a gene- and context-dependent way. They don’t typically recruit RNA Pol II directly to promoters in a universal, promoter-by-promoter manner. Instead, they recruit coactivator complexes and facilitate enhancer-promoter looping, thereby increasing or repressing transcription in response to signals or conditions. So the best description is that general transcription factors are required for transcription of any gene by helping RNA Pol II bind promoters, whereas locus-specific factors provide the regulation that tunes transcription in particular contexts.

The key idea is how transcription is initiated by different players: general transcription factors are part of the basal machinery, while locus-specific transcription factors provide gene- and context-specific regulation.

General transcription factors are required for transcription initiation by RNA polymerase II at nearly all genes. They assemble at the core promoter to form the pre-initiation complex and help RNA Pol II recognize and bind the promoter, enabling transcription to start. This makes them essential for transcription across the genome, not just for a subset of genes.

Locus-specific transcription factors, on the other hand, bind to DNA elements such as enhancers or specific promoter sequences to modulate transcription in a gene- and context-dependent way. They don’t typically recruit RNA Pol II directly to promoters in a universal, promoter-by-promoter manner. Instead, they recruit coactivator complexes and facilitate enhancer-promoter looping, thereby increasing or repressing transcription in response to signals or conditions.

So the best description is that general transcription factors are required for transcription of any gene by helping RNA Pol II bind promoters, whereas locus-specific factors provide the regulation that tunes transcription in particular contexts.