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Receptor Tyrosine Kinase Signaling

by Kevin Ahern, PhD
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    Next I’d like to talk about another very interesting set of receptor proteins. These are known as the receptor tyrosine kinase proteins and they’re involved in very important signaling that help to control the cell’s decision to divide or not to divide. Now, receptor tyrosine kinases or RTKs are also membrane bound proteins. And these are also kinases. That means that they put phosphates onto other proteins. But unlike protein kinase A which puts phosphates onto serines and threonines, RTKs put phosphates onto the side chains of tyrosines of target proteins. And it turns out that phosphorylation of tyrosines gives a very different kind of a signal than phosphorylation of serines and threonines. We can see the phosphorylation of tyrosine happening as a result of catalysis by RTK in this process right here, and they’re simply the addition of a phosphate to the hydroxyl group of tyrosine. RTKs play very important roles as I said in regulating whether or not cells are going to divide. Now RTKs usually work as a result of dimerization. What does that mean? Well RTKs are found in cell membranes as individual units; an RTK here and an RTK over here. Each of those individual units as they exist will be inactive, but the binding of a hormone causes the two subunits, or the two units of the protein to actually come together into one, that’s a dimer. That dimer is then active. So the activation of an RTK happens by the binding of the hormone that causes dimerization of individual subunits. We see schematically here, two RTKs, individual subunits embedded in a lipid bilayer. There’s the lipid bilayer. And we see the outside of the cell is at the top and the inside of the cell is to the bottom. The RTK monomers have...

    About the Lecture

    The lecture Receptor Tyrosine Kinase Signaling by Kevin Ahern, PhD is from the course Hormones and Signal Transduction. It contains the following chapters:

    • Receptor Tyrosine Kinase Signaling
    • Means of Activation
    • Insulin Receptor

    Included Quiz Questions

    1. They autophosphorylate on binding their hormone.
    2. They are active primarily as monomers.
    3. They remove phosphate from proteins.
    4. All of the answers are true.
    5. None of the answers are true.
    1. It requires dimerization.
    2. It can occur on the outside or inside of the cell.
    3. It turns off the signaling system.
    4. All of the answers are true.
    5. None of the answers are true.
    1. All of the answers are true.
    2. It has proteins that bind to phosphotyrosines.
    3. It has proteins with SH2 domains.
    4. It communicates the message to the rest of the cell.
    5. None of the answers are true.
    1. It activates phosphoprotein phosphatase.
    2. It inactivates phosphoprotein phosphatase.
    3. It causes blood glucose levels to rise.
    4. All of the answers are true.
    5. None of the answers are true.
    1. All of the answers are true.
    2. ...has a kinase cascade like the epinephrine receptor pathway does.
    3. ...stimulates the movement of a receptor protein to the cell surface.
    4. ...favors glycogen synthesis.
    5. None of the answers are true.

    Author of lecture Receptor Tyrosine Kinase Signaling

     Kevin Ahern, PhD

    Kevin Ahern, PhD


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