FL receptors expressed in TKO cells are mannosylated on V-region glycosylation sites. (A) TKO cells were transduced with the respective HCs and LCs. Receptor surface expression of cYFP-positive cells expressing receptor FL A103, its V-region glycosylation-defective mutant FL A103gm, with glutamine replacing asparagine in the glycosylation sequon, the empty vector control, and control receptor BCR53 that was isolated from a healthy human mature B cell are shown. FACS analysis was performed using anti-human LC and anti-murine IgM antibodies. (B) FL receptor surface expression in TKO cells was compared with receptor surface expression on a primary FL sample. λ LC expression on IgM⁺-gated cells is shown. (C-D) Surface binding profile of indicated glycan-specific lectins to the designated receptors expressed on TKO cells. (E) ConA binding to FL receptor expressed on TKO cells in comparison with a primary FL sample. (F) Western blot analysis of total cell lysate and isolated surface proteins of TKO cells transduced with receptor FL A103 and FL A103gm subjected to glycosidase treatment as indicated. Size shift was analyzed by immunoblotting against anti-μHC. Data are representative of ≥3 independent experiments. EV, empty vector; TCL, total cell lysate.