NOP2

NOP2, or nucleolar protein 2, is a highly conserved nuclear protein that localizes mainly to the nucleolus. It is implicated in ribosome biogenesis, particularly in the processing and maturation of ribosomal RNA (rRNA). In many species, NOP2 is believed to function as a SAM-dependent RNA methyltransferase, contributing to chemical modifications of rRNA that help assemble functional ribosomes.

NOP2 proteins are present across eukaryotes, with known homologs in yeast (Nop2p), plants, and animals. In Saccharomyces cerevisiae, Nop2p is essential for viability and participates in pre-rRNA processing steps required for 60S subunit maturation.

In higher eukaryotes, NOP2 is frequently associated with other nucleolar components and is thought to participate in maturation pathways for multiple rRNA species. The exact substrates and mechanism vary among species, and NOP2 is often studied within the broader context of ribosome biogenesis and nucleolar stress responses.

Clinical and biological studies have reported altered NOP2 expression in rapidly proliferating cells and some cancers, suggesting a link to cell growth. However, the functional significance and causality remain areas of active research.

Ongoing work seeks to clarify its enzymatic activity, interaction partners, and role in disease.