Receptortyrosinkinázok

Receptortyrosinkinázok (RTKs) are a large family of transmembrane receptor proteins that play crucial roles in cellular signaling pathways. They are involved in a wide range of physiological processes, including cell growth, differentiation, metabolism, and survival. The defining characteristic of RTKs is their intracellular tyrosine kinase domain, which catalyzes the transfer of a phosphate group from ATP to tyrosine residues on specific substrate proteins.

RTKs are typically activated by the binding of extracellular ligands, such as growth factors, hormones, and cytokines. Upon ligand binding, the RTKs dimerize, bringing their intracellular kinase domains into close proximity. This proximity allows for autophosphorylation of tyrosine residues within the kinase domain and on the receptor itself. These phosphorylated tyrosine residues serve as docking sites for downstream signaling molecules, initiating a cascade of intracellular events.

The signaling pathways activated by RTKs are diverse and often overlap, allowing for complex and context-dependent cellular responses. Key signaling pathways include the Ras-MAPK pathway, PI3K-Akt pathway, and JAK-STAT pathway. Dysregulation of RTK signaling is implicated in numerous diseases, particularly cancer, where mutations or overexpression of RTKs can lead to uncontrolled cell proliferation and survival. Consequently, RTKs are important targets for therapeutic interventions, with many approved drugs designed to inhibit specific RTK activity.