Acts as a chaperone during the assembly of the 26S proteasome, specifically of the PA700/19S regulatory complex (RC). In the initial step of the base subcomplex assembly is part of an intermediate PSMD10:PSMC4:PSMC5:PAAF1 module which probably assembles with a PSMD5:PSMC2:PSMC1:PSMD2 module. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Molecular Function: protein binding; transcription factor binding
Biological Process: anaphase-promoting complex-dependent proteasomal ubiquitin-dependent protein catabolic process; antigen processing and presentation of exogenous peptide antigen via MHC class I, TAP-dependent; cytoplasmic sequestering of NF-kappaB; inhibition of NF-kappaB transcription factor; MAPKKK cascade; negative regulation of apoptosis; negative regulation of DNA damage response, signal transduction by p53 class mediator; negative regulation of MAPKKK cascade; negative regulation of transcription from RNA polymerase II promoter; negative regulation of ubiquitin-protein ligase activity during mitotic cell cycle; positive regulation of cell growth; positive regulation of cyclin-dependent protein kinase activity; positive regulation of proteasomal ubiquitin-dependent protein catabolic process; positive regulation of protein ubiquitination; positive regulation of ubiquitin-protein ligase activity during mitotic cell cycle; proteasomal ubiquitin-dependent protein catabolic process; protein polyubiquitination; regulation of amino acid metabolic process; regulation of mRNA stability; stimulatory C-type lectin receptor signaling pathway; T cell receptor signaling pathway; tumor necrosis factor-mediated signaling pathway; Wnt receptor signaling pathway, planar cell polarity pathway