Component of the PAT complex, an endoplasmic reticulum (ER)-resident membrane multiprotein complex that facilitates multi-pass membrane proteins insertion into membranes (PubMed:32814900). The PAT complex acts as an intramembrane chaperone by directly interacting with nascent transmembrane domains (TMDs), releasing its substrates upon correct folding, and is needed for optimal biogenesis of multi-pass membrane proteins (PubMed:32814900). WDR83OS/Asterix is the substrate-interacting subunit of the PAT complex, whereas CCDC47 is required to maintain the stability of WDR83OS/Asterix (PubMed:12475939, PubMed:32814900). WDR83OS/Asterix associates with the first transmembrane domain (TMD1) of the nascent chain, independently of the N-glycosylation of the chain and irrespective of the amino acid sequence and transmembrane topology of TMD1 (PubMed:12475939, PubMed:32814900). The PAT complex favors the binding to TMDs with exposed hydrophilic amino acids within the lipid bilayer and provides a membrane-embedded partially hydrophilic environment in which TMD1 binds (PubMed:32814900). The PAT complex includes WDR83OS/Asterix and CCDC47. Belongs to the Asterix family.