Eukaryotic translation initiation factor 3 subunit B

EIF3B (eukaryotic translation initiation factor 3 subunit B) is an RNA-binding component of the eIF-3 complex, a core regulator of protein synthesis initiation (UniProt: P55884). The protein facilitates recruitment of initiation factors to the 40S ribosome, promotes mRNA scanning for AUG recognition, and enables recycling of post-termination complexes. EIF3B also selectively modulates translation of mRNAs involved in cell proliferation, differentiation, and apoptosis through context-dependent activation or repression.

EIF3B is broadly expressed across tissues and participates in fundamental translation machinery pathways. UniProt records no specific disease annotations for this protein in its curated disease database.

EIF3B is up-regulated in Alzheimer's disease brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of 0.47 across two subcellular fractions from a TMT-labeled proteomics study of post-mortem AD brain. This elevation suggests altered translation initiation capacity may accompany AD pathology, though the functional consequences of increased eIF-3B remain to be determined.