FIGURE 8.

Synergism between mutations in functional motifs and the ΔE mutation and dual role of Kar2/BiP in torsinA and torsinAΔE degradation. A, defect in N-linked glycosylation triggers the Kar2/BiP-dependent degradation of torsinAΔE. CHX chases were performed as described before (see legend for Fig. 3). KAR2 (A and C) and kar2-1 (B and D) strains expressing torsinA or torsinAΔE containing (A and B) Asn-Gln mutations that prevent glycosylation at Asn-143 (N143Q) and Asn-158 (N158Q). (*, p < 0.0004 for torsinAΔE versus torsinAΔE-N158Q in the KAR2 strain); or mutations in the Walker-A motif (K108A) or Walker-B motif (E171Q) (C and D). (*, p < 0.0007 for torsinA versus torsinA-K108A in the KAR2 strain; p < 0.00001 for torsinAΔE versus torsinAΔE-K108A in the KAR2 strain; p < 0.003 for torsinAΔE versus torsinAΔE-E171Q in the KAR2 strain). Below are representative Western blots used for quantitation. Experiments were done at least twice with ≥2 independent replicates/experiment.