RNA-binding protein required for the maturation of box H/ACA snoRNPs complex and ribosome biogenesis. During assembly of the H/ACA snoRNPs complex, it associates with the complex and disappears during maturation of the complex and is replaced by GAR1 to yield mature H/ACA snoRNPs complex (By similarity). During assembly of the complex, component of the small nucleolar ribonucleoprotein particles containing H/ACA-type snoRNAs (H/ACA snoRNPs) which contains cbf5, naf1, nhp2 and nop10 proteins. Absent from the nucleolus. Belongs to the NAF1 family.