Binds specifically to cytosolic chaperonin (c-CPN) and transfers target proteins to it. Binds to nascent polypeptide chain and promotes folding in an environment in which there are many competing pathways for nonnative proteins. Heterohexamer of two PFD-alpha type and four PFD-beta type subunits (By similarity). Component of the PAQosome complex which is responsible for the biogenesis of several protein complexes and which consists of R2TP complex members RUVBL1, RUVBL2, RPAP3 and PIH1D1, URI complex members PFDN2, PFDN6, PDRG1, UXT and URI1 as well as ASDURF, POLR2E and DNAAF10/WDR92 (PubMed:31738558). Interacts with URI1; the interaction is phosphorylation-dependent and occurs in a growth-dependent manner (PubMed:17936702). Belongs to the prefoldin subunit beta family.