title: LRIG1 extracellular domain: structure and function analysis.
abstract: We have expressed and purified three soluble fragments of the human LRIG1-ECD (extracellular domain): the LRIG1-LRR (leucine-rich repeat) domain, the LRIG1-3Ig (immunoglobulin-like) domain, and the LRIG1-LRR-1Ig fragment using baculovirus vectors in insect cells. The two LRIG1 domains crystallised so that we have been able to determine the three-dimensional structures at 2.3Å resolution. We developed a three-dimensional structure for the LRIG1-ECD using homology modelling based on the LINGO-1 structure. The LRIG1-LRR domain and the LRIG1-LRR-1Ig fragment are monomers in solution, whereas the LRIG1-3Ig domain appears to be dimeric. We could not detect any binding of the LRIG1 domains or the LRIG1-LRR-1Ig fragment to the EGF receptor (EGFR), either in solution using biosensor analysis or when the EGFR was expressed on the cell surface. The FLAG-tagged LRIG1-LRR-1Ig fragment binds weakly to colon cancer cells regardless of the presence of EGFRs. Similarly, neither the soluble LRIG1-LRR nor the LRIG1-3Ig domains nor the full-length LRIG1 co-expressed in HEK293 cells inhibited ligand-stimulated activation of cell-surface EGFR.
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
authors.forename: Yibin
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Soo
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Francesca
authors.initials: F
authors.lastname: Walker
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
authors.forename: Hui Hua
authors.initials: HH
authors.lastname: Zhang
authors.affiliation: Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Redpath
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Chin Wee
authors.initials: CW
authors.lastname: Tan
authors.affiliation: Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Nicos A
authors.initials: NA
authors.lastname: Nicola
authors.affiliation: CSIRO Manufacturing Flagship, Parkville, Victoria 3052, Australia.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Adams
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Garrett
authors.affiliation: Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: zhang@wehi.edu.au.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Zhang
authors.affiliation: Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Department of Surgery, RMH, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: tburgess@wehi.edu.au.
authors.forename: Antony W
authors.initials: AW
authors.lastname: Burgess
mesh_terms: D015374:Biosensing Techniques; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D018360:Crystallography, X-Ray; D066246:ErbB Receptors / Q000737:chemistry* / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D000090263:Leucine-Rich Repeat Proteins; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance; D014407:Tumor Cells, Cultured
chemical_list: C484445:LRIG1 protein, human; D000090263:Leucine-Rich Repeat Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D011506:Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: EGFR inhibition; LINGO-1; leucine-rich repeat domain; stem cell marker