Figure 7: The length of the Htt polyglutamine stretch governs the availability of Hip-1 to bind to Hippi.
a, 293 cells stably expressing Htt with polyglutamine repeats of various lengths (15 or 128 repeats) were transiently transfected with Hip-1, Hippi or both. Co-immunoprecipitation of Hip-1 with Hippi in various conditions was examined by western blot using an anti-Hip-1 antibody. Expression of equivalent amounts of Hip-1, Hippi, and Htt mutants was confirmed by western blot on 50 μg cell lysate. Molecular mass markers are on the right. b, The intensity of the signal corresponding to the amount of Hip-1 co-immunoprecipitated with Hippi from 293 cells overexpressing wild-type Htt-Q(15) or mutant Htt-Q(128) was quantified by laser densitometry and compared to the signal from cells with endogenous level of Htt. A reference value of 100% binding was given to the level of interaction between Hip-1 and Hippi in 293 cells expressing only endogenous Htt (first column). The values are the average of four independent experiments and are significant, with P < 0.003 in t-tests.
