tyrosinreseptor

Tyrosinreseptor, commonly referred to in the context of receptor tyrosine kinases (RTKs), denotes a family of cell-surface receptors that initiate signaling cascades after binding extracellular ligands. The binding event typically induces receptor dimerization and autophosphorylation on tyrosine residues in the cytoplasmic kinase domain, creating docking sites for downstream signaling proteins.

Upon activation, RTKs recruit adaptor proteins and enzymes that propagate signals through pathways such as the MAPK/ERK, PI3K-Akt, and PLCγ cascades. These pathways regulate essential cellular processes, including proliferation, differentiation, survival, metabolism, migration, and angiogenesis. RTK signaling is tightly controlled by receptor internalization, degradation, phosphatases, and feedback inhibitors.

Structure and activation: RTKs are single-pass transmembrane proteins with an extracellular ligand-binding domain, a single transmembrane helix, and an intracellular tyrosine kinase domain. Ligand binding promotes dimerization, trans-autophosphorylation, and assembly of signaling complexes.

Examples: the epidermal growth factor receptor (EGFR), fibroblast growth factor receptors (FGFRs), platelet-derived growth factor receptors (PDGFRs), and vascular endothelial growth factor receptors (VEGFRs), as well as insulin receptor family members, are classical RTKs. Abnormal RTK activity is implicated in cancer, developmental disorders, and metabolic diseases.

Clinical relevance: RTKs are frequent drug targets. Therapeutic strategies include tyrosine kinase inhibitors and monoclonal antibodies that block ligand binding or receptor activity, providing targeted treatments in several cancers and other diseases.