RNA Polymerase

Eukaryotic RNA polymerases are essential enzymes that catalyse the synthesis of RNA molecules from DNA templates during transcription. In eukaryotes, there are three main classes—RNA polymerase I, RNA polymerase II, and RNA polymerase III—each with distinct roles and characteristics. RNA Polymerase I (RNAPI) is responsible for transcribing ribosomal RNA (rRNA) genes, which are essential for ribosome assembly and protein synthesis. RNAPI recognizes a specific promoter element called the ribosomal DNA promoter (rDNA promoter). This promoter contains an element called the core promoter, which is bound by the upstream binding factor (UBF) and the selectivity factor 1 (SL1) complex. RNAPI synthesizes a single large precursor RNA molecule (45S rRNA), which is later processed into 18S, 5.8S, and 28S rRNA species. RNAPI is sensitive to the inhibitor actinomycin D, which is used in research to selectively inhibit rRNA synthesis. RNA Polymerase II (RNAPII) is the primary RNA polymerase responsible for transcribing protein-coding genes, as well as some non-coding RNAs. RNAPII recognizes a variety of promoters, including those with TATA boxes, initiator elements, and enhancer elements. It requires the assembly of a preinitiation complex (PIC) that includes general transcription factors (GTFs) and RNA polymerase II. RNAPII synthesizes mRNA precursors (pre-mRNAs), which undergo extensive post-transcriptional processing, including splicing, capping, and polyadenylation, before becoming mature mRNAs. RNAPII is not sensitive to actinomycin D but can be inhibited by α-amanitin. RNA Polymerase III (RNAPIII) transcribes small RNA genes, including transfer RNA (tRNA) genes, 5S ribosomal RNA (rRNA) genes, and some small nuclear RNA (snRNA) genes. RNAPIII recognizes promoter elements upstream of the transcription start site. For example, tRNA genes contain an A and B box promoter elements recognized by the transcription factor TFIIIC, whilst the 5S rRNA gene has an unusual internal promoter. RNAPIII synthesizes short RNA molecules, such as tRNAs, 5S rRNAs, and snRNAs, which are crucial for various cellular processes, including protein synthesis and splicing. RNAPIII is also sensitive to α-amanitin but resistant to actinomycin D. All three eukaryotic RNA polymerases are large, multi-subunit complexes. RNAPI has 14 subunits, RNAPII has 12 subunits, and RNAPIII has 17 subunits. These subunits play various roles in transcription initiation, elongation, and termination. Each RNA polymerase has distinct promoter recognition mechanisms, allowing for gene-specific regulation. Transcription factors and coactivators help recruit the appropriate RNA polymerase to specific genes, and transcription can be regulated by various factors and signalling pathways. RNA polymerases also terminate transcription differently. RNAPI terminates transcription at specific termination sequences, whilst RNAPII and RNAPIII rely on polyadenylation and cleavage signals to terminate transcription and release the RNA transcript. Thus, eukaryotic RNA polymerases I, II, and III are specialized RNA-synthesizing enzymes with distinct roles in gene and RNA molecule transcription. They recognize different promoters, produce various types of RNA molecules, and are subject to regulation by various protein factors. We provide a wide product catalogue of research tools for investigating RNA polymerase, including RNA polymerase II CTD repeat YSPTSPS antibodies, KIAA1967 antibodies, POLR1C antibodies, RNA polymerase II RBP8 antibodies, and BS69 antibodies. Explore our full RNA polymerase product range below and discover more, for less.