Relocalization of the pre-BCR at the pre-B/stromal cell synapse depends on pre-BCR/GAL1/integrin interactions. (A) GST-hλ5UR, GST-mλ5UR, and GST proteins were preincubated with sepharose glutathione beads before incubation with recombinant hGAL1. Coprecipitated proteins were revealed by Western blot using anti-GAL1 AS or anti-GST mAbs. (B-D) Large pre-BII/OP9 cocultures were performed without or with the following: 40 μg/mL mSLC, mSLCΔ, or mSLCΔΔ; 100 μg/mL GST-mλ5UR or control GST (B); 0.2 M of the indicated carbohydrate (C); 20 μg/mL anti-α4 and -β2 blocking Abs or an isotype control (D). The percentage of cells with a relocalized pre-BCR was determined by confocal microscopy after anti-IgM staining. For each condition, 121 to 487 cells were examined. The histograms represent the percentage of inhibition of pre-BCR relocalization compared with controls (at least 3 independent experiments). The recombinant proteins used in panel B are schematically represented above the histogram. Errors bars represent SD.