THE MURINE AIDS VIRUS GAG PRECURSOR PROTEIN BINDS TO THE SH3 DOMAIN OF C-ABL

The Pr60(gag) protein of the murine AIDS (MAIDS) defective virus promo tes the proliferation of the infected target B cells and is responsibl e for inducing a severe immunodeficiency disease. Using the yeast two- hybrid system, we identified the SH3 domain of c-Abl as interacting wi th the proline-rich p12 domain of pr60(gag). The two proteins were sho wn to associate in vitro and in vivo in MAIDS virus-infected B cells. Overexpression of Pr60(gag) in these cells led to a detectable increas e of the levels of c-Abl protein and to its translocation at the membr ane. These results suggest that this viral protein serves as a docking site for signaling molecules and that c-Abl may be involved in the pr oliferation of infected B cells.