NAF1 is a 494 amino acid RNA-binding protein belonging to the NAF1 family. Encoded by a gene that maps to human chromosome 4q32.2, NAF1 associates with mature RNA in cell lysates and is essential for ribosome biogenesis, premessenger RNA splicing, stable RNA accumulation, maturation of box snoRNP complexes and telomere maintenance. NAF1 mobilizes at the site of transcription where it binds to and escorts the core protein Dyskerin between the nucleus and cytoplasm. NAF1 is replaced by GAR1, which binds competitively with NAF1, resulting in mature RNPs in Cajal bodies and nucleoli. NAF1 delocalizes to the cytoplasm during overexpression but NAF1 shuttling properties continue to be operative. Dyskeratosis congenita mutations in human telomerase RNA may affect NAF1 assembly function.