FIGURE 1.

Co-expression of Mesd enhances secretion of LRP6 β-propellers. A, schematic representation of HA-tagged LRP6 BP constructs. BP, β-propeller. Each of the BPs (β-propeller/EGF module) is depicted in comparison to the full-length LRP6. The four BP domains are labeled with 1, 2, 3, and 4. B, soluble LRP6 containing all four BP domains (BP1234) was well secreted, and Mesd co-expression enhanced its maturation and secretion. BP1234 were transiently transfected into BHK570 cells, with or without Mesd co-transfection. Secretion of soluble BP1234 was allowed to proceed for 48 h, concentrated, followed by Western blot analysis of both conditioned media and cellular lysates. Data show one representative experiment done in triplicate, and β-actin was used as a loading control. C, the percentage of secretion was calculated by the quantitation of Western blots from three independent experiments. ^**, p < 0.01 compared with pcDNA co-transfected cells.