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- Gherardi, E, et al.
(författare)
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Structural basis of hepatocyte growth factor/scatter factor and MET signalling
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 103:11, s. 4046-4051
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Tidskriftsartikel (refereegranskat)abstract
- The polypeptide growth factor, hepatocyte growth factor/scatter factor (HGF/SF), shares the multidomain structure and proteolytic mechanism of activation of plasminogen and other complex serine proteinases. HGF/SF, however, has no enzymatic activity. Instead, it controls the growth, morphogenesis, or migration of epithelial, endothelial, and muscle progenitor cells through the receptor tyrosine kinase MET. Using small-angle x-ray scattering and cryo-electron microscopy, we show that conversion of pro(single-chain)HGF/SF into the active two-chain form is associated with a major structural transition from a compact, closed conformation to an elongated, open one. We also report the structure of a complex between two-chain HGF/SF and the MET ectodomain (MET928) with 1:1 stoichiometry in which the N-terminal and first kringle domain of HGF/SF contact the face of the seven-blade β-propeller domain of MET harboring the loops connecting the β-strands b–c and d–a, whereas the C-terminal serine proteinase homology domain binds the opposite “b” face. Finally, we describe a complex with 2:2 stoichiometry between two-chain HGF/SF and a truncated form of the MET ectodomain (MET567), which is assembled around the dimerization interface seen in the crystal structure of the NK1 fragment of HGF/SF and displays the features of a functional, signaling unit. The study shows how the proteolytic mechanism of activation of the complex proteinases has been adapted to cell signaling in vertebrate organisms, offers a description of monomeric and dimeric ligand-receptor complexes, and provides a foundation to the structural basis of HGF/SF-MET signaling.
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- Klaile, E, et al.
(författare)
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The CEACAM1 N-terminal Ig domain mediates cis- and trans-binding and is essential for allosteric rearrangements of CEACAM1 microclusters
- 2009
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 187:4, s. 553-567
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Tidskriftsartikel (refereegranskat)abstract
- Cell adhesion molecules (CAMs) sense the extracellular microenvironment and transmit signals to the intracellular compartment. In this investigation, we addressed the mechanism of signal generation by ectodomains of single-pass transmembrane homophilic CAMs. We analyzed the structure and homophilic interactions of carcinoembryonic antigen (CEA)–related CAM 1 (CEACAM1), which regulates cell proliferation, apoptosis, motility, morphogenesis, and microbial responses. Soluble and membrane-attached CEACAM1 ectodomains were investigated by surface plasmon resonance–based biosensor analysis, molecular electron tomography, and chemical cross-linking. The CEACAM1 ectodomain, which is composed of four glycosylated immunoglobulin-like (Ig) domains, is highly flexible and participates in both antiparallel (trans) and parallel (cis) homophilic binding. Membrane-attached CEACAM1 ectodomains form microclusters in which all four Ig domains participate. Trans-binding between the N-terminal Ig domains increases formation of CEACAM1 cis-dimers and changes CEACAM1 interactions within the microclusters. These data suggest that CEACAM1 transmembrane signaling is initiated by adhesion-regulated changes of cis-interactions that are transmitted to the inner phase of the plasma membrane.
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