Summary
PDB 1RY7 deposited: 2003-12-19 modified: 2009-02-24
Title Crystal Structure of the 3 Ig form of FGFR3c in complex with FGF1
Authors Basilico, C., Eliseenkova, A.V., Ibrahimi, O.A., Linhardt, R.J., Mohammadi, M., Olsen, S.K., Raucci, A., Schlessinger, J., Yayon, A., Zhang, F.
Method X-RAY DIFFRACTION
Structure factors resolution 3.2 rfactor 0.277 rfree 0.341
DPI 1.54 theoretical min: 0.89
Citations

The prototypical fibroblast growth factor receptor (FGFR) extracellular domain consists of three Ig domains (D1-D3) of which the two membrane-proximal D2 and D3 domains and the interconnecting D2-D3 linker bear the determinants of ligand binding and specificity. In contrast, D1 and the D1-D2 linker are thought to play autoinhibitory roles in FGFR regulation. Here, we report the crystal structure of the three-Ig form of FGFR3c in complex with FGF1, an FGF that binds promiscuously to each of the seven principal FGFRs. In this structure, D1 and the D1-D2 linker are completely disordered, demonstrating that these regions are dispensable for FGF binding. Real-time binding experiments using surface plasmon resonance show that relative to two-Ig form, the three-Ig form of FGFR3c exhibits lower affinity for both FGF1 and heparin. Importantly, we demonstrate that this autoinhibition is mediated by intramolecular interactions of D1 and the D1-D2 linker with the minimal FGF and heparin-binding D2-D3 region. As in the FGF1-FGFR2c structure, but not the FGF1-FGFR1c structure, the alternatively spliced betaC'-betaE loop is ordered and interacts with FGF1 in the FGF1-FGFR3c structure. However, in contrast to the FGF1-FGFR2c structure in which the betaC'-betaE loop interacts with the beta-trefoil core region of FGF1, in the FGF1-FGFR3c structure, this loop interacts extensively with the N-terminal region of FGF1, underscoring the importance of the FGF1 N terminus in conferring receptor-binding affinity and promiscuity. Importantly, comparison of the three FGF1-FGFR structures shows that the flexibility of the betaC'-betaE loop is a major determinant of ligand-binding specificity and promiscuity.

Proc.Natl.Acad.Sci.Usa 2004 Jan; 101(4):935-940 doi:10.1073/pnas.0307287101

Cross References
Database source Identifier Description
PubMed 14732692 PNASA6
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
1RY7/1 1RY7 1 dimer 0 2 0 2541