Biomaterial Database

All-atom structural models for complexes of insulin-like growth factors IGF1 and IGF2 with their cognate receptor. 2010

Harish Vashisth, and Cameron F Abrams

Department of Chemical and Biological Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA. hl332@drexel.edu

Type 1 insulin-like growth factor receptor (IGF1R) is a membrane-spanning glycoprotein of the insulin receptor family that has been implicated in a variety of cancers. The key questions related to molecular mechanisms governing ligand recognition by IGF1R remain unanswered, partly due to the lack of testable structural models of apo or ligand-bound receptor complexes. Using a homology model of the IGF1R ectodomain IGF1RDeltabeta, we present the first experimentally consistent all-atom structural models of IGF1/IGF1RDeltabeta and IGF2/IGF1RDeltabeta complexes. Our explicit-solvent molecular dynamics (MD) simulation of apo-IGF1RDeltabeta shows that it displays asymmetric flexibility mechanisms that result in one of two binding pockets accessible to growth factors IGF1 and IGF2, as demonstrated via an MD-assisted Monte Carlo docking procedure. Our MD-generated ensemble of structures of apo and IGF1-bound IGF1RDeltabeta agrees reasonably well with published small-angle X-ray scattering data. We observe simultaneous contacts of each growth factor with sites 1 and 2 of IGF1R, suggesting cross-linking of receptor subunits. Our models provide direct evidence in favor of suggested electrostatic complementarity between the C-domain (IGF1) and the cysteine-rich domain (IGF1R). Our IGF1/IGF1RDeltabeta model provides structural bases for the observation that a single IGF1 molecule binds to IGF1RDeltabeta at low concentrations in small-angle X-ray scattering studies. We also suggest new possible structural bases for differences in the affinities of insulin, IGF1, and IGF2 for their noncognate receptors.

UI	MeSH Term	Description	Entries
D008961	Models, Structural	A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)	Model, Structural,Structural Model,Structural Models
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013002	Somatomedins	Insulin-like polypeptides made by the liver and some fibroblasts and released into the blood when stimulated by SOMATOTROPIN. They cause sulfate incorporation into collagen, RNA, and DNA synthesis, which are prerequisites to cell division and growth of the organism.	Sulfation Factor,Somatomedin,Factor, Sulfation
D017526	Receptor, IGF Type 1	A protein-tyrosine kinase receptor that is closely related in structure to the INSULIN RECEPTOR. Although commonly referred to as the IGF-I receptor, it binds both IGF-I and IGF-II with high affinity. It is comprised of a tetramer of two alpha and two beta subunits which are derived from cleavage of a single precursor protein. The beta subunit contains an intrinsic tyrosine kinase domain.	IGF Type 1 Receptor,IGF-I Receptor,Receptor, IGF-I,Receptor, Insulin-Like Growth Factor I,Receptor, Insulin-Like Growth Factor Type 1,IGF-1 Receptor,Insulin-Like-Growth Factor I Receptor,Receptor, IGF Type 1 alpha Subunit,Receptor, IGF Type 1 beta Subunit,Receptors, IGF-1,Receptors, Insulin-Like-Growth Factor I,IGF 1 Receptor,IGF I Receptor,IGF-1 Receptors,Insulin Like Growth Factor I Receptor,Receptor, IGF I,Receptor, IGF-1,Receptors, IGF 1
D017527	Receptor, IGF Type 2	A receptor that is specific for IGF-II and mannose-6-phosphate. The receptor is a 250-kDa single chain polypeptide which is unrelated in structure to the type 1 IGF receptor (RECEPTOR, IGF TYPE 1) and does not have a tyrosine kinase domain.	IGF Type 2 Receptor,IGF-II Receptor,Receptor, IGF-II,Receptor, Insulin-Like Growth Factor II,Receptor, Insulin-Like Growth Factor Type 2,Receptor, Mannose-6-Phosphate,IGF-2 Receptor,Insulin-Like-Growth-Factor II Receptor,Mannose-6-Phosphate Receptor,Receptors, IGF-2,Receptors, Insulin-Like Growth Factor II,IGF 2 Receptor,IGF II Receptor,IGF-2 Receptors,Insulin Like Growth Factor II Receptor,Mannose 6 Phosphate Receptor,Receptor, IGF II,Receptor, IGF-2,Receptor, Insulin Like Growth Factor II,Receptor, Insulin Like Growth Factor Type 2,Receptor, Insulin-Like-Growth-Factor II,Receptor, Mannose 6 Phosphate,Receptors, IGF 2,Receptors, Insulin Like Growth Factor II
D056004	Molecular Dynamics Simulation	A computer simulation developed to study the motion of molecules over a period of time.	Molecular Dynamics Simulations,Molecular Dynamics,Dynamic, Molecular,Dynamics Simulation, Molecular,Dynamics Simulations, Molecular,Dynamics, Molecular,Molecular Dynamic,Simulation, Molecular Dynamics,Simulations, Molecular Dynamics