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Mol. Cell. Biol., 01 1996, 37-44, Vol 16, No. 1
F Romero, C Dargemont, F Pozo, WH Reeves, J Camonis, S Gisselbrecht and S Fischer
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.
Copyright © 1996, American Society for Microbiology
p95vav associates with the nuclear protein Ku-70
Institut Cochin de Genetique Moleculaire, U363 Institut National de la Sante et de la Recherche Medicale (INSERM), Hopital Cochin, Paris, France.
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