Elongation, termination and RNA processing:

The TFIIH has two functions.  It is a helicase that means in which it can use ATP to unwind the DNA helix, permitting transcription to start. Additionally, it phosphorylates RNA polymerase II that causes this enzyme to modification its conformation and dissociate from other proteins in the initiation complex. The RNA polymerase II now begins moving  along  the  DNA  template, synthesizing  RNA, which is, the procedures enters the elongation phase. The main phosphorylation occurs on a long C-terminal tail known as the C-terminal domain (CTD) of the RNA polymerase II molecule. Interestingly only RNA polymerase II which has a nonphosphorylated CTD can initiate transcription but only an RNA polymerase II with a phosphorylated CTD can elongate RNA.

The RNA molecule made from a protein-coding gene through RNA polymerase II is known as a primary transcript. Until the conditions in prokaryotes the main transcript from a eukaryotic protein-coding gene  is a precursor  molecule, pre-mRNA, which requires  extensive  RNA  processing in order to yield mature mRNA ready for translation. Various RNA  processing  reactions are included that are as follows: capping, 3'  cleavage and polyadenylation and RNA  splicing a number of the enzymes included in the processing steps become related with the RNA transcript by initial interaction with the CTD of RNA polymerase II and then transfer to the growing RNA molecule so the CTD is also essential for switching RNA processing. Therefore, in eukaryotes, elongation through RNA polymerase II is tightly coupled to RNA processing. The Elongation of the RNA chain keep going on until termination occurs. Expects RNA polymerase in prokaryotes RNA polymerase II doesn't terminate transcription at a specific site but rather transcription can stop at varying distances down- stream of the gene.

Figure: Initiation of transcription by RNA polymerase II. TFIID binds to the TATA box followed in order by the binding of TFIIA, TFIIB and a pre-formed complex of TFIIF.RNA polymerase II. Subsequently TFIIE and TFIIH bind in order and transcription then starts about 25 bp down- stream from the TATA box. Note that the placement of the various factors in this diagram is arbitrary; their exact positions in the complex are not known.