Transcriptional Control

by Georgina Cornwall, PhD

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    00:00 Let us take a look at transcriptional control. There are lots of players. When I introduced you to transcription, I said you didn't need to know all of their names, I will hold true to that here. Let us look. This is the first one that attaches. When our first general transcription factor, we are just going to put them in that class, attaches, it will signal others to join, so many others join. These transcription factors are necessary for any level of transcription.

    00:32 If we don't have all of them, we don't have transcription. Lots of different proteins need to be transcribed and translated elsewhere in the genome for this one gene to even be transcribed. Once we have all of these transcription factors in place, polymerase can join. RNA polymerase II, in this case, is going to join the party and connect to these transcription factors and we might be ready to go. But in addition, there may be some transcription associated factors. Other factors that are necessary for time dependent or tissue dependent transcription. They are not absolutely necessary for transcription to happen, but in some cells, we need these accessory or extra transcription factors in order to make transcription happen at a particular time or condition or whatever cell type. So those are some of the players involved in putting together this initiation complex for transcription. There is more that comes into play. We need to have some activation. Sometimes you may recall that I introduced the idea that once polymerase leaves the station starts transcribing, it may pause fairly close to the promoter region and that is where we need to have some activator proteins, some special other proteins to push it on down the track and say yep you are okay, you are good to go. We are learning more and more about these enhancer regions.

    02:17 Enhancer regions are on the DNA. It is a DNA code that is the enhancer region and then we have some specific transcription factors and I would like for you to just call them activators for now, but they are specific transcription factors that may help to push the process along even faster. These activators, specific transcription factors will bind to the enhancer region when it is time to go. Polymerase and all of its transcription factors that are necessary may be some additional transcription factors if it is time dependent thing and then the activator bound to the enhancer region and that enhancer region is far away from the actual genes on the DNA and so it being far away in order to make any contact, it has to loop. We have noticed these loops form in order to get the active enhancers to activate the transcription factors and the polymerase and push it further down the strand. Let us look at a little closer at how this could happen.

    03:29 There are another couple of players that come in. We have got a general transcription factors.

    03:32 We have got a polymerase. We have got all of that up and the promoter region for the gene we were interested in. We then have activators, which we will look at in a little bit more detail and then coactivators that help the activators associate with the whole transcription complex. So here we go, a little closer view, we have got our core promoter with our transcription factors and the polymerase and may be an additional transcription factor, one of those TIFs and now we have some enhancer regions that will have bound to them, activator proteins, specific other transcription factors.

    04:13 Transcription factors is a really used term to say something that helps in the process of transcription. We sort of say it is a transcription factor. Another transcription factor is called the activator because it is going to activate it and when they are bound to the enhancer, we will get that loop around. We have to have some coactivators to help them bind to that whole transcription process and push it along the way. There is a lot of pieces to this puzzle and there is more and more being learned every day. You don't need to know the names of all of the transcription factors because it would just become too much, you sort of lose the process in learning all the names of them. But they appear and it all comes together and activators could push it faster down the tracks.

    About the Lecture

    The lecture Transcriptional Control by Georgina Cornwall, PhD is from the course Gene Regulation.

    Included Quiz Questions

    1. Multiple transcription factors
    2. RNA Polymerase II
    3. Transcription associated factors (TAF's)
    4. Activator Proteins
    5. Enhancer regions
    1. DNA looping transports the transcription factor closer to the promoter and initiates gene transcription.
    2. The transcription factor transcribes small RNAs that then bind to the promoter and activate the gene's expression.
    3. Signals originate via inducers from the transcription factor to the site of promotion that activate transcription of the gene.
    4. The assistance of RNA looping moves the transcription factor closer to the promoter.
    1. …can be located away from the gene, upstream or downstream from the transcription start point.
    2. …is a cis-acting region of NA composed of 50-1500 base-pairs.
    3. …is a part of the core promoter region composed of -35 and -10 elements.
    4. …is a part of the promoter region, where the RNA pol starts to unwind the DNA duplex.

    Author of lecture Transcriptional Control

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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