Dyskerin binds the H/ACA box of human telomerase RNA and is a core telomerase subunit required for RNP biogenesis and enzyme function in vivo. Missense mutations in dyskerin result in dyskeratosis congenita, a complex syndrome characterized by bone marrow failure, telomerase enzyme deficiency, and
Rat Nap57 and its yeast homologue Cbf5p are pseudouridine synthases involved in rRNA biogenesis, localized in the nucleolus. These proteins, together with H/ACA class of snoRNAs compose snoRNP particles, in which snoRNA guides the synthase to direct site-specific pseudouridylation of rRNA. In this