Structural features of the full-length adaptor protein GADS in solution determined using small-angle X-ray scattering.

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TitleStructural features of the full-length adaptor protein GADS in solution determined using small-angle X-ray scattering.
Publication TypeJournal Article
Year of Publication2008
AuthorsMoran, O, Roessle, MW, Mariuzza, RA, Dimasi, N
JournalBiophys J
Date Published2008 Mar 1
KeywordsAdaptor Proteins, Signal Transducing, Chromatography, Gel, Protein Binding, Receptors, Antigen, T-Cell, Scattering, Small Angle, Solutions, T-Lymphocytes, X-Ray Diffraction

The Grb2-related adaptor protein GADS plays a central role during the initial phases of signal transduction in T lymphocytes. GADS possesses N- and C-terminal Src homology 3 (SH3) domains flanking a central Src homology 2 (SH2) domain and a 126-residue region rich in glutamine and proline residues, presumed to be largely unstructured. The SH2 domain of GADS binds the adaptor protein LAT; the C-terminal SH3 domain pairs GADS to the adaptor protein SLP-76, whereas the function of the central region is unknown. High-resolution three-dimensional models are available for the isolated SH2 and C-terminal SH3 domains in complex with their respective binding partners, LAT and SLP-76. However, in part because of its intrinsic instability, there is no structural information for the entire GADS molecule. Here, we report the low-resolution structure of full-length GADS in solution using small-angle x-ray scattering (SAXS). Based on the SAXS data, complemented by gel filtration experiments, we show that full-length GADS is monomeric in solution and that its overall structural parameters are smaller than those expected for a protein with a long unstructured region. Ab initio and rigid body modeling of the SAXS data reveal that full-length GADS is a relatively compact molecule and that the potentially unstructured region retains a significant degree of structural order. The biological function of GADS is discussed based on its overall structure.

Alternate JournalBiophys. J.
PubMed ID17993503
PubMed Central IDPMC2242750