Fig. 11.

Possible roles of eIF4E1, eIF4E2 and eIF4E3 in translation inititation and mRNA repression. Abundant and tightly regulated eIF4E1 plays an important role both in translation initiation and translation repression and therefore localizes to sites of active translation, PBs and SGs. The major role of eIF4E2 is in translation repression and therefore localizes mainly to PBs. Different composition of SGs as a consequence of different stresses and dynamic flux of molecules between PBs and SGs is suggested by the presence of eIF4E2 in SGs after heat shock but not sodium arsenite treatment. Low abundant eIF4E3_A may serve as a keeper of basal translation initiation which is not regulated by 4E-BP pathway and is not involved in mRNA repression and decay pathways. eIF4E3_A thus localizes to SGs but never to PBs upon stresses. Colour coding is the same as in other figures: eIF4Es are in green, PBs are in blue and SGs are in red. For simplification, we do not include other eIF4E1 regulatory pathways and shuttling of all three eIF4Es between cytoplasm and nucleus