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. 2018 Mar 19;115(14):E3155–E3162. doi: 10.1073/pnas.1704639115

Fig. 5.

Fig. 5.

Dimeric sorting motifs mediate ER export via the COPII coat. (A) Schematics of a homodimeric FF–FF motif or a heterodimeric FF–AA motif. (B) LMAN1-AA inhibits ER export of the wild-type LMAN1 revealed by the proximity assay. 293A cells stably expressing SAR1B-BirA* were transfected with the indicated LMAN1 mutants and treated with 15 µM biotin for 4 h. After cell lysis, biotinylated proteins were isolated by streptavidin beads and subjected to SDS/PAGE followed by immunoblotting with the indicated antibodies. (C) LMAN1-AA traps wild-type LMAN1 in the ER. HeLa cells expressing the indicated LMAN1 constructs were fixed and subjected to immunostaining with the indicated antibodies, followed by confocal microscopy. (Scale bars, 8 µm.) (D) Dimeric FY, LL, LV, and IL sorting motifs in ER export. 293A cells stably expressing SAR1-BirA* were transfected with Myc-LMAN1 mutants with the indicated sorting motifs and treated with 15 µM biotin for 4 h. After cell lysis, biotinylated proteins were isolated by streptavidin beads and subjected to SDS/PAGE followed by immunoblotting with an anti-Myc antibody.