Question

Differentiate between RNA polymerase I, RNA polymerase II and RNA polymerase III.

Answer 1

Feature	RNA Polymerase I	RNA Polymerase II	RNA Polymerase III
Primary Transcripts	Precursor of ribosomal RNAs (rRNA): 18S, 5.8S, and 28S.	Pre-messenger RNA (mRNA), snRNA, microRNA.	Transfer RNA (tRNA), 5S rRNA, and other small RNAs.
Location	Nucleolus	Nucleoplasm	Nucleoplasm
α-Amanitin Sensitivity	Insensitive (not affected by the toxin).	Highly sensitive (inhibited by very low concentrations).	Moderately sensitive (inhibited by higher concentrations).
Number of Subunits	14 subunits.	12 subunits.	17 subunits
Transcript Volume	Responsible for 50-60% of total cellular RNA.	Transcribes the widest variety of genes.	Produces many short, high-turnover non-coding RNAs.