Figure 5.

Degradation of TGN38 isoforms. Cells were treated with cycloheximide for 0–3 h at 37°C to inhibit protein synthesis. TGN38 variants were precipitated from cell lysates with a sheep polyclonal antibody to TGN38 (shG29) and immunoblotted with a rabbit polyclonal antibody to TGN38 (1918). Protein levels were compared by densitometry, and results are expressed as percentage of total initial TGN38 variant remaining at each time point (±SD, n = 3). In one experiment, cells expressing S331D were preincubated in the presence of a mixture of lysosomal inhibitors (LPEM) for 2 h before the addition of cycloheximide and throughout the 3-h time course (n = 1).