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 (B)</p> Signup and view all the answers

In what way do different EGFR ligands stabilize receptor dimers?

<p>By forming distinct structures (D)</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 (C)</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 (D)</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> (A)</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. (C)</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. (D)</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. (A)</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 (C)</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. (C)</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. (B)</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 (D)</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. (C)</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 (B)</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 (C)</p> Signup and view all the answers

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

<p>Receptor becomes fully activated (A)</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 (C)</p> Signup and view all the answers

What creates docking sites for numerous signaling effectors?

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

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

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

What leads to the activation of a negative feedback event?

<p>Recruitment of downstream signal transducers (C)</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 (D)</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 (A)</p> Signup and view all the answers

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