Functional map and domain structure of MET, the product of the c-met protooncogene and receptor for hepatocyte growth factor/scatter factorGherardi, E., Youles, M. E., Miguel, R. N., Blundell, T. L., Iamele, L., Gough, J., Bandyopadhyay, A., Hartmann, G., Butler, P. J., Functional map and domain structure of MET, the product of the c-met protooncogene and receptor for hepatocyte growth factor/scatter factor. Proc. Natl. Acad. Sci. U.S.A., 100 (21), pp. 12039–12044. October 2003. No electronic version available.
Little is known about the large ectodomain of MET, the product of the c-met protooncogene and receptor for hepatocyte growth factor/scatter factor (HGF/SF). Here, we establish by deletion mutagenesis that the HGF/SF and heparin-binding sites of MET are contained within a large N-terminal domain spanning the alpha-chain (amino acids 25-307) and the first 212 amino acids of the beta-chain (amino acids 308-519). Neither the cystine-rich domain (amino acids 520-561) nor the C-terminal half of MET (amino acids 562-932) bind HGF/SF or heparin directly. The MET ectodomain, which behaves as a rod-shaped monomer with a large Stokes radius in solution, binds HGF/SF in the absence or presence of heparin, and forms a stable HGF/SF-heparin-MET complex with 1:1:1 stoichiometry. We also show that the ligand-binding domain adopts a beta-propeller fold, which is similar to the N-terminal domain of alphaV integrin, and that the C-terminal half contains four Ig domains (amino acids 563-654, 657-738, 742-836, and 839-924) of the unusual structural E set, which could be modeled on bacterial enzymes. Our studies provide 3D models and a functional map of the MET ectodomain. They have broad implications for structure-function of the MET receptor and the related semaphorin and plexin proteins.