title: Dynamic interaction of CD2 with the GYF and the SH3 domain of compartmentalized effector molecules.
abstract: Intracellular protein interaction domains are essential for eukaryotic signaling. In T cells, the CD2BP2 adaptor binds two membrane-proximal proline-rich motifs in the CD2 cytoplasmic tail via its GYF domain, thereby regulating interleukin-2 production. Here we present the structure of the GYF domain in complex with a CD2 tail peptide. Unlike SH3 domains, which use two surface pockets to accommodate proline residues of ligands, the GYF domain employs phylogenetically conserved hydrophobic residues to create a single interaction surface. NMR analysis shows that the Fyn but not the Lck tyrosine kinase SH3 domain competes with CD2BP2 GYF-domain binding to the same CD2 proline-rich sequence in vitro. To test the in vivo significance of this competition, we used co-immunoprecipitation experiments and found that CD2BP2 is the ligand of the membrane-proximal proline-rich tandem repeat of CD2 in detergent-soluble membrane compartments, but is replaced by Fyn SH3 after CD2 is translocated into lipid rafts upon CD2 ectodomain clustering. This unveils the mechanism of a switch of CD2 function due to an extracellular mitogenic signal.
authors.affiliation: Protein Engineering Group and Molecular Modeling Group, Forschungsinstitut für Molekulare Pharmakologie and Freie Universität Berlin, Robert-Rössle-Strasse 10, D-13125 Berlin, Germany. freund@fmp-berlin.de
authors.forename: Christian
authors.initials: C
authors.lastname: Freund
authors.forename: Ronald
authors.initials: R
authors.lastname: Kühne
authors.forename: Hailin
authors.initials: H
authors.lastname: Yang
authors.forename: Sunghyouk
authors.initials: S
authors.lastname: Park
authors.forename: Ellis L
authors.initials: EL
authors.lastname: Reinherz
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagner
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D018801:CD2 Antigens / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002455:Cell Division; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008213:Lymphocyte Activation / Q000502:physiology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010802:Phylogeny; D011392:Proline / Q000737:chemistry; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D020449:Repetitive Sequences, Amino Acid; D016415:Sequence Alignment; D012995:Solubility; D013347:Subcellular Fractions / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018801:CD2 Antigens; C120378:CD2BP2 protein, human; D002352:Carrier Proteins; D008024:Ligands; D011518:Proto-Oncogene Proteins; D011392:Proline; C494957:FYN protein, human; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051076:Proto-Oncogene Proteins c-fyn