Download MendeleyCrystal structure of the alpha1beta1 integrin I-domain: insights into integrin I-domain function.
Nolte, M., Pepinsky, R.B., Venyaminov, S.Y.u., Koteliansky, V., Gotwals, P.J., Karpusas, M.(1999) FEBS Lett 452: 379-385
- PubMed: 10386626
- DOI: https://doi.org/10.1016/s0014-5793(99)00666-3
- Primary Citation of Related Structures:
1CK4 - PubMed Abstract:
The alpha1beta1 integrin is a major cell surface receptor for collagen. Ligand binding is mediated, in part, through a 200 amino acid inserted 'I'-domain contained in the extracellular part of the integrin alpha chain. Integrin I-domains contain a divalent cation binding (MIDAS) site and require cations to interact with integrin ligands. We have determined the crystal structure of recombinant I-domain from the rat alpha1beta1 integrin at 2.2 A resolution in the absence of divalent cations. The alpha1 I-domain adopts the dinucleotide binding fold that is characteristic of all I-domain structures that have been solved to date and has a structure very similar to that of the closely related alpha2beta1 I-domain which also mediates collagen binding. A unique feature of the alpha1 I-domain crystal structure is that the MIDAS site is occupied by an arginine side chain from another I-domain molecule in the crystal, in place of a metal ion. This interaction supports a proposed model for ligand-induced displacement of metal ions. Circular dichroism spectra determined in the presence of Ca2+, Mg2+ and Mn2+ indicate that no changes in the structure of the I-domain occur upon metal ion binding in solution. Metal ion binding induces small changes in UV absorption spectra, indicating a change in the polarity of the MIDAS site environment.
Organizational Affiliation:
Biogen, Inc., Cambridge, MA 02142, USA.
