Biology 2382B Lecture Notes - Lecture 11: Gtpase, Sarcoma, Platelet-Derived Growth Factor
Document Summary
Ligands include growth factors (ngf, pdgf, fgf, egf) and insulin. Cytoplasmic domain with intrinsic tyrosine kinase activity which is stimulated by ligand binding due to receptor dimerization. Ras acts as a gtpase switch protein to signal further downstream kinases. Aberrant signaling is at root of many human cancers. Activation of rtks o o dimerization allows for trans- autophosphorylation of cytoplasmic domains phosphotyrosines serve as docking sites for downstream signal- transduction proteins containing sh2 or ptb domains (adapter proteins): the cytosolic domain of rtks. Adapter proteins contains a protein tyrosine kinase catalytic site. In the absence of ligand (1) the rtks exist as monomers with poorly active kinases. Ligand binding causes a conformational change that promotes formation of a functional dimeric receptor, brining together two poorly active kinases that then phosphorylate each other on a tyrosine residue in the activation lip (2).
