box H/ACA snoRNP complex
box h/aca snornp complex
"A box H/ACA small nucleolar ribonucleoprotein complex located in the nucleolus that catalyzes pseudouridylation of ribosomal RNA residues. The complex is composed of four different core proteins that assemble onto a H/ACA guide RNA scaffold that identifies specific uridines in rRNA for modification during ribosome synthesis."