Figure 5.

 hIre1p contains high-mannose core oligosaccharides. Transfected COS-1 cells that overexpress hIre1p were pulse labeled with [³⁵S]methionine and cysteine for 15 min in the presence (lane 2) or absence (lane 1) of tunicamycin and cell extracts were prepared. In parallel, cells pulse labeled 15 min in the absence of tunicamycin were incubated 3 hr in medium containing excess unlabeled methionine and cysteine before harvesting cell extracts. The ³⁵Slabeled hIre1p was immunoprecipitated from cell extracts and analyzed by SDS-PAGE. Prior to SDS-PAGE, immunoprecipitated samples were incubated in the absence (lanes 1–3) or presence (lane 4) of endoglycosidase H.