FIG. 4.
Homodimerization of LRP6 receptors on the cell surface. (A) Analysis of cell surface expression of wild-type and mutant LRP6 receptors. Forty-eight hours following transfection of 293T cells with 2 μg of Flag-tagged wild-type LRP6, LRP6ΔE1-4, LRP6ΔE1-2, or LRP6ΔE3-4 construct, living cells were processed for immunostaining with anti-myc (control) or anti-Flag antibody and were subjected to FACS analysis as described in Materials and Methods. (B) Dimerization of wild-type and mutant LRP6 receptors on the cell surface. Forty-eight hours following transfection of 293T cells with 2 μg of Flag-tagged wild-type LRP6, LRP6ΔE1-4, LRP6ΔE1-2, or LRP6ΔE3-4 construct, cross-linking was performed on intact cells in the presence (+) or absence (−) of BS3 as described in Materials and Methods. Cell lysates were immunoprecipitated with anti-Flag M2 agarose beads and were subjected to SDS-PAGE followed by immunoblotting with anti-Flag antibody. M, monomer; D, dimer.
