Members of this family are nucleolar RNA-associated proteins (Nrap) which are highly conserved from yeast (Saccharomyces cerevisiae) to human. In the mouse, Nrap is ubiquitously expressed and is specifically localised in the nucleolus [1]. Nrap is a large nucleolar protein (of more than 1000 amino acids). Nrap appears to be associated with ribosome biogenesis by interacting with pre-rRNA primary transcript [1]. This domain has a nucleotidyltransferase structure.

1: Isolation and characterization of a new nucleolar protein, Nrap, that is conserved from yeast to humans. Utama B, Kennedy D, Ru K, Mattick JS; Genes Cells 2002;7:115-132. PMID:11895476