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.