Based on limited published evidence, NOPCHAP1 is a client-loading cofactor of the PAQosome/R2TP chaperone complex that specifically selects NOP58 to facilitate box C/D small nucleolar ribonucleoprotein (snoRNP) assembly 1. It acts as a bridge between NOP58 and the R2TP complex by directly interacting with both the CC-NOP domain of NOP58 and domain II of RUVBL1/2 AAA+ ATPases 1. NOPCHAP1 exhibits selectivity for NOP58 over related CC-NOP proteins like NOP56 and PRPF31, with NOP58 expression decreased in NOPCHAP1 knockout cells 1.