Eukaryotic initiation factor 3 subunit K (eIf3K) is one of at least 13 non-identical protein subunits of eukaryotic initiation factor 3 (eIF3). eIF3 is the largest eIF (~650 kDa) and functions to facilitate binding of the 40S ribosomal subunit to the 5’-end of cellular mRNAs near the cap structure (m7GpppN). eIF3 has been found to localize to both the nucleus and cytoplasm. In the cytoplasm, eIf3K associates with keratin 18 in intermediate filaments of epithelial cells and may have an apoptosis-promoting function. It also has been shown to interact with cyclin D3.