FIGURE 7.

Kar2/BiP maintains torsinA and torsinAΔE membrane association and solubility. Microsomes prepared from log phase wild-type (KAR2) or kar2-1 yeast cells grown at 28 °C and that express torsinA (T) or torsinAΔE (ΔE) were incubated for 30 min in ice in pH 6.8 buffer or pH ∼11.5 carbonate buffer (A) or in a pH 6.8 buffer containing 1% Triton X-100 (B). After centrifugation at 100,000 × g, aliquots of proteins from the supernatant (S) or the pellet (P) fractions were separated by SDS-PAGE, and the presence of torsinA and torsinAΔE was detected by Western blot analysis and quantified. Significant p values for the carbonate extraction are as follows: *, p < 0.001 for KAR2 torsinA versus kar2-1 torsinA; p < 0.001 for KAR2 torsinAΔE versus kar2-1 torsinAΔE; ^¥, p < 0.02 for kar2-1 torsinA versus kar2-1 torsinAΔE; and for Triton extraction are as follows: *, p < 0.008 KAR2 torsinA versus kar2-1 torsinA; p < 0.002 for KAR2 torsinAΔE versus kar2-1 torsinAΔE. C, graph shows the means ± S.E. of the fraction of torsinA or torsinAΔE remaining in the pellet from at least three independent experiments.