Fig. 3. Steady-state distributions of wild-type and mutant FcRn in polarized IMCD cells measured by binding Fc at the apical or basolateral cell surface. Cell monolayers on Transwells were incubated at 4°C with ¹²⁵I-Fc at the apical or basolateral surface with or without excess unlabeled IgG. Binding in the presence of competing IgG was considered non-specific and was subtracted from the total. Specific Fc binding at each surface is represented as a percentage of the total specific binding at both surfaces. Columns represent the mean apical and basolateral percentage±s.e.m. from triplicate samples from one experiment representative of 2-5 experiments.