Fig. 1. Effect of metabolic stress on surface labelling of GLUT1 in Clone 9 cells by a membrane-impermeant photoaffinity reagent. Clone 9 cells were incubated with or without 5 mM sodium azide for 30 minutes, as indicated, then photolabelled with 500 µM Bio-LC-ATB-BMPA in the absence or presence of 400 mM glucose (lane 3) or 20 µM cytochalasin B (lane 4). A control sample (lane 5) was also UV-irradiated in the absence of Bio-LC-ATB-BMPA. Following cell lysis with 1% TX-100, samples of total lysate proteins (a) and of biotinylated cell-surface proteins isolated by adsorption to streptavidin agarose (b) were subjected to western blotting to detect GLUT1, as described in the Materials and Methods. The mobilities of the molecular mass markers are indicated on the left.