Association of sdAb19 with Nef. HeLa (A) or 293T (B) cells were transfected with the vector for expression of the c-Myc–tagged sdAb19 in combination with vector for expression of either Nef-GFP or GFP. (A) Intracellular distribution of Nef-GFP and sdAb19. sdAb19 was detected by indirect immunofluorescence with anti–c-Myc in Nef-GFP– (middle and bottom) or GFP-expressing cells (top). (B) Coimmunoprecipitation of Nef-GFP and sdAb19. Cell lysates (right) were submitted to immunoprecipitation with anti–c-Myc (left) or anti-GFP (center). Immunoprecipitates were analyzed by Western blotting with the use of anti-c-Myc (bottom) or anti-GFP (top). IP indicates immunoprecipitate.