ER egress of class I molecules is faster in C282Y mutants. (A) After 2.5 hours ³⁵S-metabolic labeling, W6/32 immunoprecipitates were digested for 6 hours at 37°C with Endo H, n-Glycosidase F, or mock treated and separated by 10% SDS-PAGE. The position of the resistant and sensitive forms of MHC class I HCs is indicated (R and S, respectively). Molecular weight markers are shown on the left. (B) Digestion-resistant and -sensitive class I forms were quantified by phosphoimaging and are presented as an R/S ratio. ^*Statistically significant difference between the C282Y mutants and the control cells (P < .05). Data are representative of 5 independent experiments, each performed with cells from one WT control blood donor and one C282Y homozygous patient with HH.