Crystal structure of human insulin-like growth factor-1: detergent binding inhibits binding protein interactions.Vajdos, F.F., Ultsch, M., Schaffer, M.L., Deshayes, K.D., Liu, J., Skelton, N.J., de Vos, A.M.
(2001) Biochemistry 40: 11022-11029
- PubMed: 11551198
- DOI: https://doi.org/10.1021/bi0109111
- Primary Citation of Related Structures:
- PubMed Abstract:
Despite efforts spanning considerably more than a decade, a high-resolution view of the family of proteins known as insulin-like growth factors (IGFs) has remained elusive. IGF-1 consists of three helical segments which are connected by a 12-residue linker known as the C-region. NMR studies of members of this family reveal a dynamic structure with a topology resembling insulin but little structural definition in the C-region. We have crystallized IGF-1 in the presence of the detergent deoxy big CHAPS, and determined its structure at 1.8 A resolution by multiwavelength anomalous diffraction, exploiting the anomalous scattering of a single bromide ion and six of the seven sulfur atoms of IGF-1. The structure reveals a well-defined conformation for much of the C-region, which extends away from the core of IGF-1 and has residues known to be involved in receptor binding prominently displayed in a type II beta-turn. In the crystal, these residues form a dimer interface, but analytical ultracentrifugation experiments demonstrate that at physiological concentrations IGF-1 is monomeric. A single detergent molecule contacts residues known to be important for IGF-1 binding protein (IGFBP) interactions. Biophysical and biochemical data show that the detergent binds to IGF-1 specifically and blocks binding of IGFBP-1 and IGFBP-3.
Department of Protein Engineering, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.