InterPro domain: IPR005351

This family represents Asterix proteins which are a component of the PAT complex, an endoplasmic reticulum (ER)-resident membrane multiprotein complex that facilitates multi-pass membrane proteins insertion into membranes [ 1 ]. The PAT complex, formed by CCDC47 and Asterix proteins, 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 [ 2 ]. WDR83OS/Asterix, ( Q9Y284 ) is the substrate-interacting subunit of the PAT complex, whereas CCDC47 is required to maintain the stability of WDR83OS/Asterix [ 2 , 2 ]. 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 [ 3 , 3 ]. 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 [ 3 ]. This entry also includes the ER membrane uncharacterised protein from Schizosaccharomyces pombe C18B11.08c.

1. An intramembrane chaperone complex facilitates membrane protein biogenesis. Nature 584, 630-634
2. Different transmembrane domains associate with distinct endoplasmic reticulum components during membrane integration of a polytopic protein. Mol Biol Cell 13, 4114-29