RNA Polymerase II (RNAPII) is the enzyme responsible for transcribing protein-coding genes into messenger RNA (mRNA) in eukaryotic cells. Several proteins are tightly associated with RNAPII, forming a transcription initiation and elongation complex. These proteins play essential roles in transcription regulation and mRNA processing. RNA polymerase-associated factors are intimately involved in promoter recognition, helping RNA polymerase identify the specific DNA sequences (promoters) where transcription should begin. Different transcription factors recognize different promoter elements, such as the TATA box, CAAT box, and GC box, ensuring that the correct genes are transcribed. Transcription factors recruit RNA polymerase to the promoter region of a gene and facilitate the formation of the transcription initiation complex. This complex includes RNA polymerase and other general transcription factors (GTFs), ensuring that transcription starts at the right position and in the correct direction. GTFs are a group of proteins that assemble with RNAPII at the promoter region of genes to initiate transcription. These factors include TFIIA, TFIIB, TFIID (which comprises TATA-binding protein, TBP), TFIIE, TFIIF, and TFIIH. They help position RNAPII at the transcription start site and unwind the DNA for transcriptional initiation. The Mediator complex is a multi-subunit protein complex that acts as a bridge between transcriptional activators, repressors, and RNAPII. It facilitates communication between transcription factors and the basal transcription machinery. Whilst it is not a direct component of the RNAPII enzyme itself, it is closely associated with RNAPII during transcription initiation and elongation. Capping enzymes involved in mRNA capping, such as capping enzyme (CE) and guanylyl transferase (GTase), are tightly associated with RNAPII during the early stages of transcription. They add a 5' cap structure to the nascent mRNA, which is essential for mRNA stability and translation. Proteins involved in RNA splicing, including various small nuclear ribonucleoproteins (snRNPs) and splicing factors, are often found associated with the C-terminal domain (CTD) of the largest subunit of RNAPII. These factors play a role in removing introns from the pre-mRNA during transcription. Proteins involved in mRNA polyadenylation, such as poly(A) polymerase (PAP), cleavage and polyadenylation specificity factor (CPSF), and cleavage stimulation factor (CstF), also interact with RNAPII during transcriptional termination. They contribute to the addition of a polyadenylate tail to the 3' end of the mRNA. Elongation factors, including Elongin and TFIIS, also associate with RNAPII during the elongation phase of transcription. They facilitate transcriptional elongation, prevent transcriptional pausing, and enhance the fidelity of transcription. Chromatin remodelling complexes, like SWI/SNF and INO80, can also interact with RNAPII to modify chromatin structure, making the DNA template more accessible for transcription. Finally, enzymes involved in histone modifications, such as histone acetyltransferases (HATs) and histone methyltransferases (HMTs), can interact with RNAPII to modify histones and regulate transcription. Thus, RNA polymerase-associated factors are essential proteins that regulate the process of transcription in eukaryotic cells. They play multiple critical roles in ensuring that RNA polymerase binds to the correct genes and initiates transcription accurately. We offer a large product range of research reagents for studying polymerase associated factors, including RNA polymerase II CTD repeat YSPTSPS antibodies, SIRT7 antibodies, HNF-4-alpha antibodies, Follistatin ELISA Kits, and GAL4 ELISA Kits. Explore our full polymerase associated factors product range below and discover more, for less. Alternatively, you can explore our Pol II Transcription, Pol III Transcription, and Pol I Transcription product ranges.