This is a family of atypical serine kinases which are found in archaea, bacteria and eukaryotes. Activity of Rio1 is vital in Saccharomyces cerevisiae for the processing of ribosomal RNA, as well as for proper cell cycle progression and chromosome maintenance. The structure of RIO1 has been determined [4].

1: Lipopolysaccharide phosphorylating enzymes encoded in the genomes of Gram-negative bacteria are related to the eukaryotic protein kinases. Krupa A, Srinivasan N; Protein Sci 2002;11:1580-1584. PMID:12021457

2: Late cytoplasmic maturation of the small ribosomal subunit requires RIO proteins in Saccharomyces cerevisiae. Vanrobays E, Gelugne JP, Gleizes PE, Caizergues-Ferrer M; Mol Cell Biol 2003;23:2083-2095. PMID:12612080

3: Rio2p: An evolutionarily conserved, low-abundant protein kinase essential for processing of 20S Pre-rRNA in Saccharomyces cerevisiae. Geerlings TH, Faber AW, Bister M, Vos JC, Raue HA; 0;0:0-0. PMID:12690111

4: Structure and activity of the atypical serine kinase Rio1. Laronde-Leblanc N, Guszczynski T, Copeland T, Wlodawer A; FEBS J 2005;272:3698-3713. PMID:16008568