title: Co-localization of Fyn with CD3 complex, CD45 or CD28 depends on different mechanisms.
abstract: The Src family protein tyrosine kinase Fyn (p59fyn) plays an important role in thymocyte development and T cell receptor (TCR) signal transduction. Fyn has been shown to associate with the TCR-CD3 complex, the protein tyrosine phosphatase CD45 and several co-receptors such as CD28 which are crucial for initiating T cell activation and proliferation. The molecular basis of how Fyn is associated with these transmembrane proteins is largely unknown. To investigate the Fyn association with the TCR-CD3 complex, CD45 and CD28 at the molecular level, various Fyn/beta-galactosidase fusion proteins were constructed and expressed in Jurkat cells. Co-localization experiments applying antibody-induced co-capping and double immunofluorescence staining techniques were used to study the association of these fusion proteins with the TCR-CD3 complex, CD45 and CD28. Our results revealed that co-localization of Fyn with the TCR-CD3 complex requires the unique N terminus whereas co-localization with CD45 depends on the unique N terminus, the Src homology (SH)3- and a functional SH2 domain. CD28 co-localizes with Fyn molecules that contain the N terminus and a functional SH2 domain. These results suggest that Fyn association with the TCR-CD3 complex, CD45 and CD28 is mediated by different molecular mechanisms.
authors.affiliation: Roche Research Center, Hoffmann-La Roche Inc., Nutley, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: zur Hausen
authors.forename: P
authors.initials: P
authors.lastname: Burn
authors.forename: K E
authors.initials: KE
authors.lastname: Amrein
mesh_terms: D018106:CD28 Antigens / Q000378:metabolism*; D017252:CD3 Complex / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007152:Immunologic Capping; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000473:pathology; D017493:Leukocyte Common Antigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D016297:Mutagenesis, Site-Directed; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D018909:src Homology Domains
chemical_list: D018106:CD28 Antigens; D017252:CD3 Complex; D046911:Macromolecular Substances; D011518:Proto-Oncogene Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D017493:Leukocyte Common Antigens