the activation of receptor tyrosine kinases is characterized by
The activation of receptor tyrosine kinases is characterized by
Answer: The activation of receptor tyrosine kinases (RTKs) is characterized by several key steps:
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Ligand Binding: RTKs are activated when specific signaling molecules, known as ligands, bind to the extracellular domain of the receptor. This binding causes the receptor to undergo a conformational change.
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Dimerization: Once the ligand binds, RTKs often dimerize. This means two receptor molecules pair up and form a structure known as a dimer. This dimerization is crucial for the subsequent activation steps.
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Autophosphorylation: The formation of dimers activates the intrinsic kinase activity of the receptors. The kinase domains phosphorylate specific tyrosine residues on the receptor itself, a process called autophosphorylation.
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Signal Transduction: The phosphorylated tyrosines serve as docking sites for various intracellular signaling proteins. These proteins contain specific domains, such as SH2 or PTB domains, which recognize and bind to the phosphorylated tyrosines.
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Cascade Activation: The binding of intracellular signaling proteins triggers a cascade of downstream signaling pathways. These pathways ultimately lead to various cellular responses such as cell division, migration, or differentiation.
Example: When epidermal growth factor (EGF) binds to its receptor, EGFR (a type of RTK), it leads to autophosphorylation and activation of MAPK/ERK signaling pathways, promoting cell growth.
Summary: The activation of receptor tyrosine kinases involves ligand binding, receptor dimerization, autophosphorylation, and subsequent activation of intracellular signaling pathways that modulate various cellular functions.
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