Component of the PAT complex, an endoplasmic reticulum (ER)-resident membrane multiprotein complex that facilitates multi-pass membrane proteins insertion into membranes. 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. WDR83OS/Asterix is the substrate-interacting subunit of the PAT complex, whereas CCDC47 is required to maintain the stability of WDR83OS/Asterix. 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. 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. The PAT complex includes WDR83OS/Asterix and CCDC47. Belongs to the Asterix family.