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.
Publication types
-
Comparative Study
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Adaptor Proteins, Signal Transducing
-
Amino Acid Motifs
-
Amino Acid Sequence
-
Binding Sites
-
Binding, Competitive
-
CD2 Antigens / chemistry
-
CD2 Antigens / metabolism*
-
Carrier Proteins / chemistry
-
Carrier Proteins / metabolism*
-
Cell Division
-
Humans
-
Hydrophobic and Hydrophilic Interactions
-
Ligands
-
Lymphocyte Activation / physiology
-
Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / metabolism
-
Membrane Microdomains / metabolism
-
Models, Molecular
-
Molecular Sequence Data
-
Nuclear Magnetic Resonance, Biomolecular
-
Phylogeny
-
Proline / chemistry
-
Protein Interaction Mapping*
-
Protein Structure, Tertiary
-
Proto-Oncogene Proteins / chemistry
-
Proto-Oncogene Proteins / metabolism*
-
Proto-Oncogene Proteins c-fyn
-
Repetitive Sequences, Amino Acid
-
Sequence Alignment
-
Solubility
-
Subcellular Fractions / metabolism
-
T-Lymphocytes / metabolism*
-
src Homology Domains
Substances
-
Adaptor Proteins, Signal Transducing
-
CD2 Antigens
-
CD2BP2 protein, human
-
Carrier Proteins
-
Ligands
-
Proto-Oncogene Proteins
-
Proline
-
FYN protein, human
-
Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
-
Proto-Oncogene Proteins c-fyn