Eukaryotic translation initiation factor 5B

EIF5B (eukaryotic translation initiation factor 5B) is a ribosome-dependent GTPase that catalyzes formation of the 80S translation initiation complex by promoting joining of the 60S ribosomal subunit to the pre-initiation complex bearing the initiator methionine-tRNA (UniProt: O60841). Working with EIF1A, it orients the initiator tRNA to facilitate 60S subunit joining, then is released after GTP hydrolysis enables EIF1A ejection to generate elongation-competent ribosomes. Its GTPase activity is required for proper ribosome maturation rather than subunit joining itself (UniProt: O60841).

EIF5B is ubiquitously expressed across tissues and participates in the core translation initiation pathway. No non-AD disease associations are annotated in UniProt for this protein.

EIF5B is tagged as upregulated in Alzheimer's disease. Proteomics analysis of human post-mortem AD brain versus age-matched controls detected elevated EIF5B abundance with a mean log2 fold-change of 0.40 across subcellular fractions (P2, P3, S2, S3) in a TMT-labeled discovery proteomics study (Chaparral AD proteomics). The functional significance of EIF5B elevation in AD pathogenesis remains to be established.