Eukaryotic initiation factor 3

In humans, eIF3 consists of 13 nonidentical subunits (eIF3a-m) with a combined molecular weight of ~800 kDa, making it the largest translation initiation factor.

[5] In specialized cases of reinitiation following uORFs, eIF3 may remain bound to the ribosome through elongation and termination to promote subsequent initiation events.

[6] Research has also indicated that eIF3 plays a role in programmed stop codon readthrough in yeast, by interacting with pre-termination complexes and interfering with decoding.

[9] All five core subunits of budding yeast's eIF3 are present in heat-induced stress granules, along with several other translation factors.

In particular, the d-subunit of eIF3 is a substrate of HIV protease, and genetic knockdown of eIF3 subunits d, e, or f results in increased viral infectivity for unknown reasons.

[19] The eIF3 subunits exist at equal stoichiometry within the complex, with the exception of eIF3J, which is loosely bound and non-essential for viability in several species.