NOP58

NOP58, or nucleolar protein 58, is a conserved eukaryotic protein that functions as a core component of box C/D small nucleolar ribonucleoproteins (snoRNPs). It localizes predominantly to the nucleolus, with some distribution in the nucleoplasm. NOP58 is broadly expressed and is essential for proper ribosome biogenesis.

In snoRNPs, NOP58 forms part of a core complex with NOP56, SNU13, and fibrillarin. The box C/D snoRNA guides direct site-specific 2'-O-methylation of ribosomal RNA, a modification important for ribosome function. NOP58 is thought to contribute to snoRNP assembly and stability, facilitating interaction between fibrillarin and the snoRNA to enable methylation. It may help recruit or stabilize snoRNPs on nascent pre-rRNA during maturation.

Evolutionarily conserved across eukaryotes, NOP58 is encoded by the NOP58 gene. The protein lacks catalytic activity itself but serves as a structural and assembly factor within snoRNPs. Interactions with fibrillarin (FBL), NOP56, and SNU13 have been reported, and NOP58 is considered a defining member of the box C/D snoRNP core.

Research on NOP58 continues to define its precise roles in snoRNP biogenesis, its regulation during the cell cycle, and its involvement in nucleolar organization. There are no widely reported disease-specific mutations directly linked to NOP58 in humans, though defects in snoRNP components can contribute to nucleolar stress and ribosome biogenesis disorders.