Cell Signaling Pathway: Ras Activation
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Questions and Answers

What is the role of ligand binding to the ECDs of EGFR receptors?

  • Causing receptor stabilization (correct)
  • Communicating with the intracellular domains of the receptor
  • Inducing cell differentiation
  • Initiating biased signaling
  • Which EGFR family member is an orphan receptor and does not recognize multiple ligands?

  • EGFR
  • HER3
  • HER2 (correct)
  • HER4
  • How do different EGFR ligands, such as EGF and TGFa, affect a cell?

  • Promoting proliferation (correct)
  • Causing receptor dimerization
  • Stimulating differentiation
  • Inducing biased signaling
  • What is the consequence of weakened dimerization of EGFR induced by Epiregulin and epigen?

    <p>Sustained EGFR signaling</p> Signup and view all the answers

    In what way do different EGFR ligands stabilize receptor dimers?

    <p>By forming distinct structures</p> Signup and view all the answers

    What is the mechanism through which the ECD dimer communicates with the intracellular domains of the receptor?

    <p>Through a still unclear mechanism</p> Signup and view all the answers

    Which type of dimers can be formed by EGFR family members with HER2?

    <p><strong>Hetero</strong>dimers</p> Signup and view all the answers

    Biased signaling is associated with the response of different EGFR ligands in a cell. What type of response is observed due to this biased signaling?

    <p><strong>Proliferation</strong></p> Signup and view all the answers

    What is the role of the adaptor protein GRB2 in the RTK-Ras/MAP kinase signaling pathway?

    <p>It promotes GTP exchange for GDP on Ras.</p> Signup and view all the answers

    In the RTK-Ras/MAP kinase signaling pathway, what is the function of Sos protein?

    <p>Activates Ras by promoting GTP exchange for GDP.</p> Signup and view all the answers

    What is the consequence of Ras activation in the RTK-Ras/MAP kinase signaling pathway?

    <p>Binds to the inner leaflet of the cytoplasmic membrane via a lipid anchor sequence.</p> Signup and view all the answers

    Which kinase is phosphorylated and activated by MAP kinase in the cytoplasm during RTK-Ras/MAP kinase signaling?

    <p>p90RSK kinase</p> Signup and view all the answers

    What is the role of ternary complex factor (TCF) and serum response factor (SRF) in the RTK-Ras/MAP kinase signaling pathway?

    <p>They are phosphorylated by p90RSK kinase and participate in gene expression.</p> Signup and view all the answers

    What is the function of MAP kinase in the RTK-Ras/MAP kinase signaling pathway?

    <p>Dimerizes and enters the nucleus.</p> Signup and view all the answers

    Which sequence controls genes, such as c-fos, that propel cells through the cell cycle?

    <p>Serum response element (SRE) enhancer sequence</p> Signup and view all the answers

    What is the consequence of Ras activation in relation to Raf kinase in the RTK-Ras/MAP kinase signaling pathway?

    <p>Promotes Raf kinase activity.</p> Signup and view all the answers

    What is the term for the formation that exposes a dimerization arm in subdomain II, thereby facilitating dimerization of the extracellular region?

    <p>Recruitment of downstream signal transducers</p> Signup and view all the answers

    What process assumes a time lag between initial receptor ligand binding and phosphorylation of tyrosines?

    <p>Kinetic proof reading</p> Signup and view all the answers

    What is the main outcome of stable complexes according to the text?

    <p>Receptor becomes fully activated</p> Signup and view all the answers

    What occurs when non-stable complexes fall apart prior to activation of negative feedback?

    <p>The complexes reform keeping the initial signaling event going</p> Signup and view all the answers

    What creates docking sites for numerous signaling effectors?

    <p>Ligand stimulation of ErbB receptor tyrosine phosphorylation</p> Signup and view all the answers

    Which ligands differenstimulate ErbB4 coupling to survival and proliferation in CEM/ formation?

    <p>NRG1β, NRG2β, and NRG3</p> Signup and view all the answers

    What leads to the activation of a negative feedback event?

    <p>Recruitment of downstream signal transducers</p> Signup and view all the answers

    What is denoted by putative sites of EGFR, ErbB2, ErbB3, and ErbB4 tyrosine phosphorylation?

    <p>Recruitment of downstream signal transducers</p> Signup and view all the answers

    What is the term used for the model that assumes a time lag between initial receptor ligand binding and phosphorylation of tyrosines?

    <p>Kinetic proof reading</p> Signup and view all the answers

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