15.5kD protein is a homologue of yeast Snu13 and archaeal L7Ae. Binds to a common kink-turn motif of RNA. Together with Nop56, Nop58 and fibrillarine they make the core of the heteromeric C/D RNP complex. It is also part of the eukaryotic pre-mRNA splicesomal RNP apparatus. The crystal structure of the human homologue has been solved (PDB ID: 1E7K, 2OZB).