PMID: 25765764

 

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Title : LRIG1 extracellular domain : structure and function analysis

Abstract :

1. We have expressed and purified three soluble fragments of the human LRIG1- ECD (extracellular domain ): the LRIG1-LRR (leucine-rich repeat) domain leucine-rich repeat) domain, the LRIG1-3Ig (immunoglobulin-like) domain , and the LRIG1- LRR-1 Ig fragment using baculovirus vectors in insect cells
2. The two LRIG1 domains crystallised so that we have been able to determine the three-dimensional structures at 2.3Å resolution
3. We developed a three-dimensional structure for the LRIG1- ECD using homology modelling based on the LINGO-1 structure
4. The LRIG1-LRR domain and the LRIG1-LRR-1Ig fragment are monomers in solution, whereas the LRIG1-3Ig domain appears to be dimeric
5. 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
6. The FLAG-tagged LRIG1-LRR-1Ig fragment binds weakly to colon cancer cells regardless of the presence of EGFRs
7. 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