MRPL4, also known as 39 S ribosomal protein L4, mitochondrial, consists of a 34.9 kDa and a 29.5 kDa isoform and is involved in mitochondrial protein synthesis as a component of the 39S ribosomal subunit. Diseases and disorders such as mycobacterium tuberculosis and pneumonia are being researched with the protein. In translation pathways, the protein interacts with DDX24, EIF2B1, ICT1, KRTAP4-12, and TIMM44.