The eIF4F and eIFiso4F Complexes of Plants: An Evolutionary Perspective

Figure 2

Domain organization of eIF4G and eIFiso4G from mammals, angiosperms, and the green algae Chlamydomonas reinhardtii. Plant eIF4G and eIFiso4G share the core organization of the eIF4E-binding site, HEAT-1/MIF4G domain, H1-CT motif, and HEAT-2/MA3 domain with mammals, but do not have the C-terminal HEAT-3 domain. The eIF3- and eIF4A-binding regions are thought to be maintained between all shown isoforms. Plant eIF4G has a longer N-terminus than mammals and contains the plant-specific 4G-PN1 and 4G-PN2 motifs as shown. Chlamydomonas eIF4G has a 4G-PN1-like sequence but no 4G-PN2 motif, while other green algae may have a 4G-PN2 motif but no 4G-PN1 motif. eIFiso4G is remarkably well conserved across plants, with the N-terminal XSLRPGG motif maintained from green algae to angiosperms.