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. Author manuscript; available in PMC: 2012 Feb 1.
Published in final edited form as: Exp Hematol. 2010 Nov 18;39(2):133–141. doi: 10.1016/j.exphem.2010.10.011

Figure 2. Formation and regulation of the ternary complex in eukaryotic translation.

Figure 2

The ternary complex is composed of eIf2, GTP and the initiator methionyl tRNA (iMet). The activity of this complex is modulated by the GTP-exchange factor eIF2B. Stress, amino acid deficiency and heme deficiency result in the activation of the eIF2 kinases which phosphorylate the α-subunit of eIF2. Phosphorylated eIF2a binds eIF2B with high affinity thereby preventing GTP/GDP exchange. Since levels of eIF2B are limiting in the cell, the net result is a reduction in translation initiation via lowered levels of the ternary complex.