CLOSE REVIEWCompare and contrast the signaling mechanisms of G-protein coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs).
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GPCRs and RTKs both initiate signaling cascades but through different mechanisms. GPCRs activate G-proteins by causing the exchange of GDP for GTP, leading to the dissociation of the G-protein into active subunits that interact with downstream effectors. In contrast, RTKs dimerize upon ligand binding and autophosphorylate their intracellular tyrosine residues, creating docking sites for signaling proteins. These proteins then propagate the signal. While GPCRs primarily use G-proteins for signal transduction, RTKs rely on phosphorylation events to activate downstream signaling pathways.
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Which of the following is a key difference between GPCRs and RTKs in their signaling mechanisms?
- A.
GPCRs and RTKs both directly bind to DNA to initiate transcription.
- B.
GPCRs activate G-proteins, while RTKs autophosphorylate and create docking sites for signaling proteins.
- C.
GPCRs use calcium ions for signaling, while RTKs use sodium ions.
- D.
GPCRs and RTKs both function as ion channels.
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