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. 2014 May 23;5:3902. doi: 10.1038/ncomms4902

Figure 1. Native MS of yeast eIF2 and eIF2B complexes.

Figure 1

(a) SDS–PAGE (insert) and mass spectrum of the purified yeast His-tagged eIF2 complex showing charge state distributions (labelled with ‘number of charges’ +) for the main species at 4,500–5,500 m/z corresponding to α/β/γ trimer (purple triangles). The α/γ dimer (red diamonds) at 4,000–4,500 m/z and γ at 3,200–3,500 m/z (blue circles) have peak splitting corresponding to a GDP molecule attached. (b) SDS–PAGE (insert) and mass spectrum of the purified yeast FLAG-tagged eIF2B complex showing the main species at 10,000–12,000 m/z corresponding in mass to the double of the eIF2B pentamer (pink star). High-collision energy results in dissociation of the α-subunit (pink circles) at 2,000 m/z and formation of the stripped complexes (14,000–16,000 m/z) where one α-subunit was lost from the eIF2B decamer (pink diamonds). The spectra shown represent an experiment from at least three biological replicates.