Mitochondrial ribosomal protein L18 (MRPL18)

Mitochondrial ribosomal protein L18 (MRPL18) is a member of the mitochondrial large ribosomal subunit and belongs to the highly conserved L18/eL5 family of 5S rRNA-binding proteins[2][5]. MRPL18 functions in the assembly and activity of mitochondrial ribosomes, playing a key role in mitochondrial protein synthesis[2][5]. MRPL18 also mediates the import of cytosolic 5S rRNA into mitochondria and interacts with other factors, such as rhodanese, to facilitate this process[2][5]. Unexpectedly, MRPL18 is also involved in the cellular response to stress (such as heat shock): during stress, an alternative translation initiation site allows production of a cytosolic MRPL18 isoform, which incorporates into cytosolic 80S ribosomes and promotes efficient translation of stress-protective proteins like Hsp70[1][3]. Knockdown of MRPL18 impairs this stress adaptation at the translational level, but has minimal short-term effects on general mitochondrial activity[1][3]. There are currently no known drugs targeting MRPL18, and it is not used as a biomarker or listed as a direct disease gene, though it is crucial for ribosome function and mitochondrial-cytosolic communication during stress responses[1][2][3][5].

Other names

MRPL18MRP-L18mitochondrial large ribosomal subunit protein L18L18/eL5 family member