What is the Difference Between RNA Polymerase Core and Holoenzyme?
🆚 Go to Comparative Table 🆚The main difference between RNA polymerase core and RNA polymerase holoenzyme lies in the presence or absence of the sigma factor. The core enzyme lacks the sigma factor, while the holoenzyme comprises the sigma factor. Here are the key differences between RNA polymerase core and RNA polymerase holoenzyme:
- Enzymes lacking sigma factor: RNA polymerase core enzymes do not have the sigma factor.
- Enzymes with sigma factor: RNA polymerase holoenzyme enzymes include the sigma factor.
- Molecular weight: The core enzyme has a molecular weight of about 400 kDa, while the holoenzyme has a molecular weight of about 419-470 kDa.
- Subunits: The core enzyme consists of α2, β, β', and ω subunits, while the holoenzyme has α2, β, β', ω, and σ subunits.
- Function in transcription: The core enzyme is involved in the elongation step of transcription, while the holoenzyme is involved in the initiation step of transcription.
In summary, the RNA polymerase core is responsible for catalytic activity in transcription, while the RNA polymerase holoenzyme is responsible for stable binding to specific promoter sequences and initiating transcription.
Comparative Table: RNA Polymerase Core vs Holoenzyme
The main difference between RNA polymerase core and RNA polymerase holoenzyme is that the core lacks the sigma factor, while the holoenzyme contains it. Here is a table summarizing the differences between RNA polymerase core and holoenzyme:
| Feature | RNA Polymerase Core | RNA Polymerase Holoenzyme |
|---|---|---|
| Subunits | α2, β, β', ω | α2, β, β', ω, σ |
| Molecular Weight | About 400 kDa | About 419-470 kDa |
| Function in Transcription | Elongation | Initiation |
| Role in Transcription | Catalytic function | Involved in initiation |
| Sigma Factor | None | Present |
The RNA polymerase core is responsible for the elongation step of transcription, while the RNA polymerase holoenzyme mainly catalyzes the initiation step of transcription. The sigma factor in the holoenzyme is crucial for ensuring that the bacterial RNA polymerase associates with the correct promoter sequence and initiates transcription.
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