Figure 2.

Mass spectrum of the apo- (A) and m⁷GDP-bound (B) forms of wild-type eIF4E. ES-MS spectra plotting ion abundance as a function of the mass/charge ratio. Insets: hypermass reconstruction of the spectrum. The low molecular weight peak at 458 is consistent with the presence of the m⁷GDP (457.23 Da). For more details, see figure legend in Supplementary Figure 3. Clearly, no cap-bound eIF4E is present in the apo sample. (C) Superposition of the ¹H-¹⁵N HSQC spectrum of the apo-eIF4E (orange) and the m⁷GDP-bound eIF4E (green). (D) The far-UV CD spectra of apo-eIF4E (orange) and m⁷GDP–eIF4E (green). (E) Fluorescence emission of wild-type eIF4E in the presence of increasing concentrations of m⁷GDP (continuous) and intrinsic fluorescence of m⁷GDP in the absence of eIF4E (dashed). The different m⁷GDP concentrations (μM) are shown on the curves and fit is shown in Supplementary Figure 2.