p95vav associates with the nuclear protein Ku-70.
The proto-oncogene vav is expressed solely in hematopoietic cells and plays an important role in cell signaling, although little is known about the proteins involved in these pathways. To gain further information, the Src homology 2 (SH2) and 3 (SH3) domains of Vav were used to screen a lymphoid cell cDNA library by the yeast two-hybrid system. Among the positive clones, we detected a nuclear protein, Ku-70, which is the DNA-binding element of the DNA-dependent protein kinase. In Jurkat and UT7 cells, Vav is partially localized in the nuclei, as judged from immunofluorescence and confocal microscopy studies. By using glutathione S-transferase fusion proteins derived from Ku-70 and coimmunoprecipitation experiments with lysates prepared from human thymocytes and Jurkat and UT7 cells, we show that Vav associates with Ku-70. The interaction of Vav with Ku-70 requires only the 150-residue carboxy-terminal portion of Ku-70, which binds to the 25 carboxy-terminal residues of the carboxy SH3 domain of Vav. A proline-to-leucine mutation in the carboxy SH3 of Vav that blocks interaction with proline-rich sequences does not modify the binding of Ku-70, which lacks this motif. Therefore, the interaction of Vav with Ku-70 may be a novel form of protein-protein interaction. The potential role of Vav/Ku-70 complexes is discussed.
Institut Cochin de Génétique Moléculaire, U363 Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Cochin, Paris, France.
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Romero
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Dargemont
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Pozo
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Reeves
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Camonis
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Gisselbrecht
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Fischer
D001483:Base Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005455:Fluorescent Antibody Technique; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051567:Proto-Oncogene Proteins c-vav; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D018909:src Homology Domains
D018797:Cell Cycle Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D009687:Nuclear Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011993:Recombinant Fusion Proteins; C496618:VAV1 protein, human; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases