FIG. 6.

Gadd34-null reticulocytes have attenuated translation initiation machinery. (A) Gadd34 expression was monitored after 3 hours of incubation with hemin. Actin is shown as a loading control. (B) Western blot of reticulocyte protein lysates following treatment with the hemoglobin synthesis activator hemin. Top, p-eIF2α(S51); bottom, total eIF2α. Densitometry was used to calculate the ratio of p-eIF2α (S51) to total eIF2α (indicated below each lane). (C) Polysome profiles from wild-type (n = 6) and Gadd34-null (n = 6) reticulocytes. Sixteen OD₂₆₀ units were loaded for each sample, and polysome-to-monosome (P/M) ratios were determined by calculating the areas under the monosome and polysome peaks. Data are presented as averages ± standard errors of the mean.