EIF3K is a subunit of the eukaryotic translation initiation factor 3 (eIF3) complex, a multi-subunit protein assembly essential for protein synthesis initiation 1. As a component of eIF3, EIF3K facilitates recruitment of initiation factors to the 40S ribosomal subunit, promotes mRNA scanning for start codon recognition, and prevents premature ribosomal subunit joining 1. Structurally, EIF3K contains a HEAT analogous motif (HAM) domain and a winged-helix (WH) domain, conferring multiple protein-binding surfaces and potential RNA-binding capacity 2. Notably, EIF3K exhibits selective mRNA regulation: its depletion paradoxically increases global translation and ribosome content by suppressing translation of ribosomal protein RPS15A, suggesting EIF3K functions as a rheostat controlling translational capacity during stress 3. Beyond canonical translation roles, EIF3K interacts with the serotonin 5-HT7 receptor to regulate its trafficking and membrane localization 4 and associates with PML nuclear bodies through its isoform eIF3K-2 5. EIF3K possesses translation-independent antiviral functions, restricting chikungunya virus production in macrophages 6. Clinically, biallelic EIF3K variants cause an autosomal recessive neurodevelopmental disorder featuring global developmental delay, microcephaly, growth retardation, and congenital heart defects 7. EIF3 subunits, including EIF3K, are frequently overexpressed in cancers, suggesting therapeutic potential 8.