The eukaryotic translation initiation factor 3 subunit J (EIF3J), also known as EIF3S1. is a critical component of the eukaryotic initiation factor 3 (eIF3) complex, which plays a central role in protein synthesis. The eIF3 complex, comprising multiple subunits, facilitates the assembly of the 43S pre-initiation complex by promoting ribosomal subunit interactions, scanning mRNA for start codons, and regulating translation initiation under various cellular conditions. EIF3J, specifically, interacts with the 40S ribosomal subunit and other eIF3 components (e.g., EIF3B) to stabilize the complex and ensure proper initiation of protein synthesis. It also participates in mRNA recruitment and ribosome recycling. Beyond its canonical role in translation, EIF3J has been implicated in cell cycle regulation, stress response, and viral infection processes. Dysregulation of EIF3J expression is associated with cancers, neurodegenerative diseases, and other pathologies, highlighting its broader cellular significance. Antibodies targeting EIF3J are essential tools for studying its expression, localization, and interactions in both physiological and disease contexts. They are widely used in techniques such as Western blotting, immunofluorescence, and immunoprecipitation to explore EIF3J’s functional mechanisms and its potential as a therapeutic or diagnostic marker. Research continues to uncover its context-dependent roles, particularly in cancer progression and translation control pathways.