Fig. 4.

The serine residue S1224 and the tyrosine residue Y1229 in the SFIGQY sequence of L1 are crucial for the recruitment of ankyrin to the plasma membrane. HEK 293 cells were cotransfected with the ankyrin–GFP expression plasmid and the following L1 expression plasmids (left labels): wild-type L1 containing the RSLE exon sequence (WT+RSLE, A–A"), the L1 point mutants L1+S1194L (S1194L, B–B") or L1+S1224L (S1224L, C–C"), or L1+Y1229H (Y1229H, D–D"). At 18 hr after transfection the cells were fixed and processed for indirect immunofluorescence staining by using antibodies specific for L1 and rhodamine-labeled secondary antibodies. The left columnpresents confocal microscopy images of immunostained L1 (L1, A–D), the middle column presents confocal microscopy images of ankyrin–GFP (ankyrin, A′–D′), and the right column presents differential interference contrast images (DIC, A"–D"). Each of thehorizontal panels (A–A" throughD–D") presents the same field of cells. Scale bar, 10 μm.