| Definition: |
A ribonucleoprotein complex that contains an RNA of the box H/ACA type and the four core proteins dyskerin, NOP10, NHP2, and GAR1 (human protein nomenclature). RNA pseudouridylation (isomerization of uridine to pseudouridine) is the major, and most likely the ancestral, function of H/ACA RNPs. Pseudouridylation targets include both large and small ribosomal RNAs (rRNAs), and small nuclear RNA (U2 snRNA). In addition to these catalytic H/ACA RNPs, a less abundant but more diverse class of structural H/ACA RNPs exists, which does not have pseudouridylation activity. These include the vertebrate telomerase RNP complex. |