Welcome to our second lecture on cell communications.
In this lecture we'll dig a little more deeply into
how second messenger systems work. First of all
we're going to be able to review a variety of
different second messenger systems. And explain
how they result in signal amplification.
And in addition to that we'll see how phosphorylation
of proteins works. And by the end of it all
you should be able to diagram a tyrosine receptor
kinase pathway as well as diagram a G-protein
coupled receptor pathway. It's pretty complicated
stuff. So let me give you an analogy to begin.
First of all, let's imagine that there is a building
on fire. I've seen the fire and I decide that I need
to call the fire department. So I ring them
quickly and I activate the emergency systems.
So the dispatch person is the receptor protein and
that dispatch person is going to activate
the firemen to go and see what's going on with the
fire and hopefully put it out. So, the bell rings
and many firemen are activated and all of those
firemen run to the scene. And then we have to have
investigators at the scene. And then we have to have
all sorts of people to find out how this fire happened.
All of this started with one signal molecule but the
response was amplified in a very large way.
This continues until the fireman have either put out
the fire or the building's burnt all the way to the ground.
The key here is that after the fire is over, the
firemen all go back to bed and relax until
the bell is rung again. So, cell communication and
signal amplification through second messenger systems
works very much in this fashion.