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Medientyp:
E-Artikel
Titel:
Mechanism of Kinase Activation in the Receptor for Colony-Stimulating Factor 1
Beteiligte:
Lee, Angel Wai-Mun;
Nienhuis, Arthur W.
Erschienen:
National Academy of Sciences of the United States of America, 1990
Erschienen in:Proceedings of the National Academy of Sciences of the United States of America
Sprache:
Englisch
ISSN:
0027-8424
Entstehung:
Anmerkungen:
Beschreibung:
<p>Receptor tyrosine kinases remain dormant until activated by ligand binding to the extracellular domain. Two mechanisms have been proposed for kinase activation: (i) ligand binding to the external domain of a receptor monomer may induced a conformational change that is transmitted across the cell membrane (intramolecular model) or (ii) the ligand may facilitate oligomerization, thereby allowing interactions between the juxtaposed kinase domains (intermolecular model). The receptor for colony-stimulating factor 1 was used to test these models. Large insertions at the junction between the external and transmembrane domains of the receptor, introduced by site-directed mutagenesis of the cDNA, were positioned to isolate the external domain and prevent transmembrane conformational propagation while allowing for receptor oligomerization. Such mutant receptors were expressed on the cell surface, bound ligand with high affinity, exhibited ligand-stimulated autophosphorylation, and signaled mitogenesis and cellular proliferation in the presence of ligand. A second experimental strategy directly tested the intermolecular model of ligand activation. A hybrid receptor composed of the external domain of human glycophorin A and the transmembrane and cytoplasmic domains of the colony-stimulating factor 1 receptor exhibited anti-glycophorin antibody-induced kinase activity that supported mitogenesis. Our data strongly support a mechanism of receptor activation based on ligand-induced receptor oligomerization.</p>