Figure 5
Vigilin is found in ER fraction. (A) HEK293 cells were homogenized and fractionated on an iodixanol gradient. Fractions were collected drop-wise and probed for vigilin, ER-resident SPP, ER-marker calnexin and Golgi apparatus-marker GM130. Vigilin was primarily found in the later (upper) fractions but a small proportion was present in the fractions 3 and 4, which also contained the peak fractions of SPP and calnexin. (B) HEK293 stably expressing vigilin-FLAG were homogenized and fractionated on an iodixanol gradient. Fractions were collected drop-wise and probed for vigilin (using anti-FLAG antibody), SPP, calnexin and GM130. Identical to the endogenous vigilin and SPP distribution, the FLAG-tagged vigilin was found mainly in the cytoplasmic fractions but also found in fraction 4, which also contained the peak fractions of SPP and calnexin.