Insights into the function and structure of the R2TP (RUVBL1-RUVBL2-RPAP3-PIH1D1) chaperone complex.

The R2TP chaperone complex comprises two AAA+ proteins, RUVBL1 and RUVBL2, along with RPAP3 and PIH1D1. R2TP functions in concert with other chaperones, such as HSP90 and HSP70, to facilitate the assembly of macromolecular complexes integral to the regulation of cell growth and proliferation. Moreover, several adaptors interact with R2TP to impart substrate specificity. Nevertheless, the precise mechanism underlying R2TP-mediated complex assembly remains unknown. This review summarizes the current knowledge regarding R2TP's involvement in the assembly, stabilization, and activity of multiple protein complexes, including box C/D and H/ACA small nucleolar ribonucleoproteins (snoRNPs), spliceosome small nuclear ribonucleoproteins (snRNPs), the tuberous sclerosis complex (TSC) , axonemal dynein arms, RNA polymerases, phosphatidylinositol 3-kinase-related kinases (PIKK), and the MRE11-RAD50-NBS1 (MRN) complex. Additionally, the role of R2TP in ciliogenesis, circadian rhythm regulation, and transcriptional condensate formation is discussed. Finally, the latest structural studies pertaining to R2TP and its related complexes are examined.