Heroin quick back and mister basics here, let's talk about eukaryotic transcription. The enzyme required for the process of transcription is the RNA polymerase. The prokaryotes have only one RNA polymerase enzyme while the eukaryotes held 3 RNA, polymerase enzyme.
RNA polymerase 2 is a major polymerase enzyme involved in a transcription of mRNA in eukaryotes. The RNA polymerase 2 along with other proteins known as the transcription factors are required for the initiation of transcription. The. Transcription factors are also known as general transcription factors, let's see how the transcription factors are designated.
The initial two letters are written as DF, which stands for transcription factor. The two indicates that it's a transcription factor for RNA. Polymerase 2, the letter next to 2 can be a b, d, e, f and h, depending on the function of transcription factor because they are so many transcription factors involved in eukaryotic transcription it's, easy to memorize them with the help of. Mnemonics, for example, the mnemonics of TFA is Apple. The F to B is ball.
Tf2D is dog TF to E is elephant. T, f2f1 TFS is helicopter let's see function of each of them in the first step of initiation of transcription. The transcription factor EF do be binds. The Tata element in the promoter. The eukaryotic promoter is about 40 nucleotides long and located upstream. And downstream of the transcription start site about 30 nucleotides upstream to the start site there's, an 80 rich sequence known as the. Tata box or data element.
Tf2D has a protein called TBB, which binds data sequence. TBP, is also known as starter binding protein once TPP binds Tata sequence. It bends the DNA by 80 degrees, this bending of DNA further helps in the binding of other transcription factors. This includes TFA and TF to be TFA TFA helps in stabilizing the binding of Ted with the promoter TFB interacts with TBP and the promoter region downstream to the data sequence TFB helps in the recruitment of RNA polymerase 2 on. The promoter now, the RNA polymerase cannot bind the promoter on its own a transcription factor, D f2f, RNA, polymerase 2 to bind the promoter d, f2, f3 and TF to be while recruiting the RNA polymerase D F to F of n, RNA polymerase to contact DNA outside the promoter.
Next transcription factor, tf2. E, binds, the pre-initiation complex tf2, II helps in the binding of other transcription factor. Tf2H TFS is a very large complex with total, nine subunits are of nine.
Two subunits help Atheist activity using. Energy from ATP, it acts like a helicase and melts, the promoter. And this finally causes transition from pre-initiation complex to open complex. The remaining seven subunits of TFS has a kinase activity. This kinase activity phosphorylates the c-terminal domain or the tail of RNA polymerase 2 leading to promoter escape and transcription elongation. So we can remember the events of transcription initiation with the following mnemonics, the dog eats the Apple and plays with the football. He gets tired.
And sits in front of the fan when he sees an elephant, he runs away in the helicopter transcription elongation once RNA polymerase help initiated transcription. It shifts into elongation phase. The transcription factors that helps in elongation are called elongation factors. There are two such elongation factors, d, Fe, b and d. F2. S, TF EB is recruited to polymerase by transcription.
Activators TF EB is a kinase protein and phosphorylates serine residues in the c-terminal domain of the polymerase. This. Phosphorylation stimulates elongation.
The other factor involved in elongation is tf2. S. Now the rate at which the RNA polymerase transcribes to DNA is not same at all DNA sequences at some DNA sequences. The rate of transcription is fast while at other DNA sequences, it can be slow tf2.
S, helps to increase the rate of transcription at the region where the rate of transcription becomes slow. It also does not allow RNA polymerase to pause and encourages moving on 5 - capping as the RNA polymerase. Starts elongation, the mRNA starts forming the formation of mRNA occurs in 5 prime to 3 prime direction. The first RNA processing that occurs during elongation is the fire - capping during this process, the terminal gamma phosphate of the nucleotide is removed by the enzyme RNA TRI phosphatase in the next step was.
Neil's transferase enzyme carries out reaction between beta phosphate of the first nucleotide and alpha phosphate of GDB once guanine is attached methyl, transferase enzyme, attaches, a. Methyl group to the guanine nucleotide. This structure is called Phi - cap. And it helps in the recruitment of mRNA on the ribosome for the initiation of translation, termination of transcription when the RNA polymerase reaches the end of the gene, the c-terminal domain of the RNA polymerase interacts with two proteins, CSF and CSF. The CSF stands for clear rate stimulation factor and CSF stands for cleavage and polyadenylation specificity factor. When the end of the gene is transcribed into RNA. These proteins are recruited to the mRNA by the c-terminal domain of RNA polymerase.
The Quebec stimulation factor CSF leaves. The mRNA once the mRNA is cleaved CSF this associates. The cps f10 recruits poly, a polymerase, which adds about 289 residues at the tree - end giving rise to poly a tail. The poly a polymerase uses ATP for this purpose once poly a tail is formed the poly a binding protein binds to poly a tail. And during the step CSF is released from the mRNA, the poly, a binding protein.
Prevents degradation of poly a tail.
Dated : 18-Apr-2022