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Receptor tyrosine kinases are a large family of cell surface receptors that play crucial roles in cellular signaling. They are integral membrane proteins that, upon binding to their specific extracellular ligands, undergo a conformational change that activates their intracellular tyrosine kinase domain. This activation leads to autophosphorylation of the receptor itself and subsequent phosphorylation of downstream signaling molecules. This cascade of phosphorylation events relays signals that regulate a wide range of cellular processes including cell growth, differentiation, survival, and metabolism.

The extracellular ligand-binding domain of receptor tyrosine kinases is highly diverse, allowing for specific recognition of various signaling molecules such as growth factors and hormones. The intracellular domain contains the catalytic tyrosine kinase activity. When a ligand binds, two receptor molecules typically dimerize, bringing their intracellular kinase domains into close proximity. This proximity is essential for trans-autophosphorylation, where each receptor phosphorylates the other on specific tyrosine residues. These phosphotyrosine sites then serve as docking sites for other intracellular proteins that contain specific recognition motifs, initiating downstream signaling pathways.

Dysregulation of receptor tyrosine kinase signaling is implicated in numerous diseases, most notably cancer. Aberrant activation due to mutations, overexpression, or autocrine signaling can drive uncontrolled cell proliferation and survival. Consequently, receptor tyrosine kinases are significant targets for therapeutic intervention, with many targeted cancer drugs designed to inhibit their activity. Examples include inhibitors of EGFR, HER2, and VEGFR. The intricate and vital roles of receptor tyrosine kinases in normal physiology and disease make them a central focus of research in cell biology and medicine.