How a single protein complex accommodates many different H/ACA RNAs

More than 100 mammalian H/ACA RNAs form an equal number of ribonucleoproteins (RNPs) by associating with the same four core proteins. The function of these H/ACA RNPs is essential for biogenesis of the ribosome, splicing of precursor mRNAs (pre-mRNAs), maintenance of telomeres and probably for additional cellular processes. Recent crystal structures of archaeal H/ACA protein complexes show how the same four proteins accommodate >100 distinct but related H/ACA RNAs and reveal that a spatial mutation cluster underlies dyskeratosis congenita, a syndrome of bone marrow failure.