Figure 5

ASNA1 interacts with VAPB via a FFAT-like motif similar to FAF1. (A) Alignment of the FFAT-like motifs in human ASNA1 and FAF1. (B) Alignment of the FFAT-like motif of ASNA1 across species showing that it is highly conserved. (C) A point mutation in the FFAT-like motif of ASNA1 (F15A) abolishes its interaction with VAPB. WT and mutant Flag-ASNA1 were immunoprecipitated from U2OS cells using anti-Flag beads. (D) Indirect immunofluorescence of VAPB and Flag-ASNA1 WT. U2OS cells were transfected with Flag-ASNA1 WT for 24 hr. Flag-ASNA1 WT (red) is co-localized with VAPB (green) in a peri-nuclear area (enlarged window) suggesting an ER pattern. Scale bar is 10 μm. (E) ASNA1 interaction with FAF1 is strongly stimulated upon proteasome inhibition with MG132 and depends on the UBA domain. WT Flag-FAF1 and the indicated mutants were immunoprecipitated from U2OS cells. (F) G46R and G46A point mutations in ASNA1 abolish its interaction with BAG6 and strongly reduce its interaction with FAF1 and ubiquitin, most noticeably after MG132 treatment, but do not affect the interaction with VAPB. WT and mutant Flag-ASNA1 were immunoprecipitated from SH-SY5Y cells. DAPI, 4',6-diamidino-2-phenylindole; IP, immunoprecipitate; WT, wild type.