Figure 9.

The endocytosis of pIgR in ldlD cells is unaffected by changes in glycosylation conditions or the presence of MUC1. The endocytosis of [³⁵S]pIgR synthesized in the presence of either 1000 μM GalNAc, with (●) or without (▪) 100 μM Gal, in ldlD cells with (B) or without (A) MUC1 coexpression was characterized as described in MATERIALS AND METHODS. Endocytosis of dimeric ¹²⁵I-labeled IgA prebound to pIgR in ldlD cell with (D) or without (C) coexpression of MUC1 was carried out after preincubation for 2 h with 1000 μM GalNAc, with (●) or without (▪) 100 μM Gal. Points are the mean of triplicate samples for representative experiments. Experiments were carried out 2–4 times with similar results. Error values at each point were <20% for both assays.