Fig. 2.

STT3B-independent glycosylation of closely spaced sites in hemopexin. (A) Diagram of hemopexin (Hpx) showing the signal sequence (black), glycosylation sites, disulfide bonds (red lines) and DDK-His tag. The five sequons are numbered 1–5; Hpx mutants lacking one or more sequons are designated as Hpx-ΔXYZ, where XYZ is the list of mutated sequon(s). HeLa cells were treated with negative control (NC) siRNA or siRNAs specific for STT3A or STT3B as indicated (B–E) for 48 hours prior to transfection with Hpx expression vectors. Cells were pulse labeled for 4 minutes and chased for 20 minutes. EH designates digestion with endoglycosidase H. Hpx glycoforms (0–5 glycans) were immunoprecipitated with anti-DDK sera and resolved by SDS-PAGE. Quantified values below gel lanes are for the displayed image that is representative of two or more experiments.