Ligand binding to receptor tyrosine kinases (such as the EGF receptor) initiates signaling by which mechanism?

• A Activation of an associated G-protein
• B Cleavage of the intracellular domain to release a transcription factor
• C Direct opening of an ion channel
• D Dimerization and autophosphorylation ✓

Explanation

Receptor tyrosine kinases are monomeric in the absence of ligand. Ligand binding induces receptor dimerization, bringing the intracellular kinase domains into proximity. This allows trans-autophosphorylation on tyrosine residues, creating docking sites for downstream signaling proteins. G-protein activation is the mechanism for GPCRs, ion channels for ligand-gated receptors, and intramembrane cleavage for Notch receptors.

Reference: Molecular Cell Biology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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