FIGURE 3.

Ag stimulation induces a physical dissociation of μm from Ig-αβ. Unstimulated M12g3r cells were fixed before μm staining (A) or were stimulated with PC₁₀BSA-gold (10 nm; large arrows) for 5 min before the preparation of native membranes, then stained for Ig-α (5 nm; small arrows; B). C, Cells expressing chimeric BCR were stimulated with NP₈BSA-gold (10 nm; large arrows) for 5 min before the preparation of native membrane then stained for Ig-α (5 nm; small arrows). D, Cells were stained with unrelated isotype-matched Ab, Her2/Neu (5 nm), after preparing native membrane sheets. Circles depict clusters of colocalized μm (10 nm) and Ig-α (5 nm). Insets, Higher magnification of association/dissociation of μm and Ig-α. The large and small arrows represent large and small gold particles. Arrowheads in A and D depict the membrane edge. Bar = 100 nm.