Fig. 1. Expression of wild-type and R664X AE1 in K562 cells. (A) Expression of bovine AE1 was examined by immunofluorescence with the monoclonal antibody cdb3-64 in K562bebWT, K562bebRX and control (K562C) cells. Bars, 10 µm. (B) K562bebWT and K562bebRX cells were pulse-labeled with [35S]methionine for 45 minutes and chased for the indicated periods. After cell-surface biotinylation, AE1 proteins were immunoprecipitated using tmb3-29 with (Surface) or without (Total) isolation on NutrAvidin beads. Migration of protein standards is indicated in kDa. Intensities of the bands at the indicated times for wild-type AE1 (WT, 105 kDa,
and
) and R664X AE1 (R664X, 75 kDa,
and
) in total (
and
) and cell-surface (
and
) fractions were determined by densitometric scanning and plotted (right). Data are the mean values of duplicate samples at each time point except for t=0 (n=3, mean ± s.d.). This procedure always produced a non-specific 77-kDa band (*) even in immunoprecipitates from control cells.