FIG 1.

(A) Murine polyomavirus MT showing associated proteins. (B) dl1015 is defective in transformation. Rat-1 fibroblasts were transfected with control vector DNA or DNA expressing either wild-type or dl1015 MT. After 2 weeks, cells were fixed and stained with crystal violet. (C) Wild-type (WT) and mutant MT sequences from residues 336 to 350. (D) MT interactions with the N-terminal SH3 of GRB2. Anti-MT immunoprecipitates from control cells or cells expressing wild-type, E349K, or 2XP MT were labeled in vitro with ³²P. MT was then reisolated and incubated with either GST-agarose or Grb2 N-SH3-GST-agarose. Washed precipitates were analyzed by PAGE and autoradiography. (E) SH3 association does not correlate with transformation. Transformation experiments performed as described for panel B compared wild-type MT to dl1015 or 2XP (P338A P341A). Expression is shown by MT blotting of equal amounts of cell protein from each cell type.