The structure of the integrin alphaIIbbeta3 transmembrane complex explains integrin transmembrane signallingLau, T.L., Kim, C., Ginsberg, M.H., Ulmer, T.S.
(2009) EMBO J 28: 1351-1361
- PubMed: 19279667
- DOI: https://doi.org/10.1038/emboj.2009.63
- Primary Citation of Related Structures:
- PubMed Abstract:
Heterodimeric integrin adhesion receptors regulate cell migration, survival and differentiation in metazoa by communicating signals bi-directionally across the plasma membrane. Protein engineering and mutagenesis studies have suggested that the dissociation of a complex formed by the single-pass transmembrane (TM) segments of the alpha and beta subunits is central to these signalling events. Here, we report the structure of the integrin alphaIIbbeta3 TM complex, structure-based site-directed mutagenesis and lipid embedding estimates to reveal the structural event that underlies the transition from associated to dissociated states, that is, TM signalling. The complex is stabilized by glycine-packing mediated TM helix crossing within the extracellular membrane leaflet, and by unique hydrophobic and electrostatic bridges in the intracellular leaflet that mediate an unusual, asymmetric association of the 24- and 29-residue alphaIIb and beta3 TM helices. The structurally unique, highly conserved integrin alphaIIbbeta3 TM complex rationalizes bi-directional signalling and represents the first structure of a heterodimeric TM receptor complex.
Department of Biochemistry and Molecular Biology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.