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Receptor Tyrosine Kinase Pathways – Second Messenger Systems

by Georgina Cornwall, PhD
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    The lecture Receptor Tyrosine Kinase Pathways – Second Messenger Systems by Georgina Cornwall, PhD is from the course Cellular Structure.


    Included Quiz Questions

    1. Most second messenger systems fall into either RTK pathways, or G-protein coupled receptor pathways
    2. RTK pathways are generally involved in regulation of normal cell processes
    3. G protein coupled pathways are generally involved in mediating structural and metabolic changes
    4. Rarely involve a multi step signal amplification
    1. ...dimerization of two protein kinase receptor subunits
    2. ...autophosphorylation
    3. ...docking proteins and adapter proteins
    4. G-protein kinases
    1. Insulin binding to the insulin-related RTKs system leads to immediate separation of two RTKs subunits to stop the down streaming of the signal cascade
    2. RTKs are membrane-embedded kinase proteins which play an important role in general cell functions like cell cycle, growth, migration, and metabolism
    3. The maintenance of blood sugar via insulin involves insulin linked RTKs system
    4. Binding of ligand to the extracellular receptor domains causes the autophosphorylation of intracellular domains at serine, threonine, and tyrosine residues
    5. Anatomical RTKs are composed of two RTKs monomer units, each with the single hydrophobic α-helical transmembrane domain, which dimerizes upon the binding of the ligand on the receptor sites
    1. Protein kinase ---- phosphorylation of proteins
    2. Docking proteins ---- Helps other proteins to get docked on the phosphotyrosine sites of RTKs
    3. Phosphotyrosine sites ---- Docking sites on RTKs for the phosphorylation of proteins
    4. Protein phosphatase ---- Dephosphorylation of proteins
    5. Adaptor proteins ---- Facilitate downstream signaling events
    1. They are involved in the organization of signaling cascade proteins/components into a highly ordered macromolecular complex for efficient signal transduction
    2. They are active enzymatic components of the signal cascade
    3. They are involved in the transfer of phosphate groups from the kinases or phosphatases to the substrate proteins to switch them on or off
    4. They directly deal with the reception of an external signal to stimulate the cellular responses
    5. They act as molecular switches
    1. The transmembrane domains of the receptor molecules act as molecular switches to phosphorylate the intracellular domains to start downstream signal transduction of external stimulus
    2. Ras, a binary signaling molecular switch (a G-protein), act as connecting links between receptor tyrosine kinases and mitogen-activated protein kinases
    3. Ras proteins are activated and deactivated by Guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), respectively
    4. Ras system usually regulates the cell cycle and division by regulating the cell cycle genes through the activation of the mitogen-activated protein (MAP) kinase cascade
    5. The breakdown of intramolecular switches leads to cancers due to deregulated cell cycle and cell division events

    Author of lecture Receptor Tyrosine Kinase Pathways – Second Messenger Systems

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD


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