Oligomerization of LMAN1 is required for MCFD2 binding. (A) Mannose binding activities of different LMAN1 mutants. COS1 cells were transfected with the wild-type and the indicated LMAN1 mutants. LMAN1 proteins that are in the cell lysate and that are eluted from the mannose agarose beads are detected by Western blot analysis. Lysate lanes represent 20% of the input added to the mannose beads. (B) Co-IP of LMAN1 mutants with MCFD2. COS1 cells were cotransfected with Flag-tagged ΔHelix or ΔHM mutant and myc-tagged wild-type MCFD2. Cell lysates were immunoprecipitated with anti-myc for MCFD2 and anti-Flag for LMAN1.