Involved in pre-rRNA processing and required for the NOP58-snoRNA interaction. Component of the R2TP complex composed at least of RVB1, RVB2, TAH1 and PIH1. Interacts also with HSP90, RRP43, NOP53 and NOP58. Present with 2610 molecules/cell in log phase SD medium. Belongs to the PIH1 family.