title: Multimeric and differential binding of CIN85/CD2AP with two atypical proline-rich sequences from CD2 and Cbl-b*.
abstract: The CD2AP (CD2-associated protein) and CIN85 (Cbl-interacting protein of 85 kDa) adaptor proteins each employ three Src homology 3 (SH3) domains to cluster protein partners and ensure efficient signal transduction and down-regulation of tyrosine kinase receptors. Using NMR, isothermal titration calorimetry and small-angle X-ray scattering methods, we have characterized several binding modes of the N-terminal SH3 domain (SH3A) of CD2AP and CIN85 with two natural atypical proline-rich regions in CD2 (cluster of differentiation 2) and Cbl-b (Casitas B-lineage lymphoma), and compared these data with previous studies and published crystal structures. Our experiments show that the CD2AP-SH3A domain forms a type II dimer with CD2 and both type I and type II dimeric complexes with Cbl-b. Like CD2AP, the CIN85-SH3A domain forms a type II complex with CD2, but a trimeric complex with Cbl-b, whereby the type I and II interactions take place at the same time. Together, these results explain how multiple interactions among similar SH3 domains and ligands produce a high degree of diversity in tyrosine kinase, cell adhesion or T-cell signaling pathways.
authors.affiliation: Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Ceregido
authors.forename: Abel
authors.initials: A
authors.lastname: Garcia-Pino
authors.forename: Jose L
authors.initials: JL
authors.lastname: Ortega-Roldan
authors.forename: Salvador
authors.initials: S
authors.lastname: Casares
authors.forename: Obdulio
authors.initials: O
authors.lastname: López Mayorga
authors.forename: Jeronimo
authors.initials: J
authors.lastname: Bravo
authors.forename: Nico A J
authors.initials: NA
authors.lastname: van Nuland
authors.forename: Ana I
authors.initials: AI
authors.lastname: Azuaga
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry*; D000595:Amino Acid Sequence; D018801:CD2 Antigens / Q000737:chemistry*; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011392:Proline; D011485:Protein Binding; D017433:Protein Structure, Secondary; D050721:Proto-Oncogene Proteins c-cbl / Q000737:chemistry*; D053838:Scattering, Small Angle; D013816:Thermodynamics; D017186:Titrimetry; D014961:X-Ray Diffraction; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018801:CD2 Antigens; C114545:CD2-associated protein; D003598:Cytoskeletal Proteins; C433810:SH3KBP1 protein, human; D011392:Proline; C492211:CBLB protein, human; D050721:Proto-Oncogene Proteins c-cbl
keywords: CIN85/CD2AP; ITC; NMR; SAXS; SH3 domain