Association of Nck with tyrosine-phosphorylated SLP-76 in activated T lymphocytes.
The Nck adaptor protein links tyrosine kinases or their substrates to proteins containing proline-rich motifs. Here we show that in activated T cells two tyrosine phosphoproteins of 75 and 120 kDa are co-immunoprecipitated with polyclonal antibodies against Nck. Analysis of Nck immunoprecipitates with various candidate antibodies revealed that the 75-kDa tyrosine phosphoprotein is the SH2 domain-containing leukocyte protein referred to as SLP-76. In vitro experiments show that the interaction between Nck and SLP-76 is mediated via the Nck SH2 domain. Using specific phosphopeptides corresponding to the major tyrosine phosphorylation sites of SLP-76, it was found that Y113 and Y128 phosphopeptides could compete binding of SLP-76 to the SH2 domain of Nck. In addition, the 120-kDa tyrosine phosphoprotein was recognized by an antibody raised against Cbl, a proto-oncogene product that has been previously found to be associated with Nck. These results suggest that the Nck adaptor protein interacts with key signaling molecules and may play an important role in activation of T lymphocytes.
Wunderlich
L
L
Department of Medical Chemistry, Semmelweis University Medical School, Budapest, Hungary.
Faragó
A
A
Downward
J
J
Buday
L
L
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000032:analysis* / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050721:Proto-Oncogene Proteins c-cbl; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000737:chemistry*; D014443:Tyrosine / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; C000715470:MAS1 protein, human; C078332:Nck protein; D015513:Oncogene Proteins; D010750:Phosphoproteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; C067419:CBL protein, human