A mixture of phosphatidylethanolamines isolated from bovine brain; comprises approximately 25% of total mammalian phospholipids and almost 50% of brain phospholipids; found mainly in the cell membrane; synthesized mainly in the ER and mitochondrial membranes; acts as a chaperone in E. coli for lactose permease assembly; cofactor for prion propagation that can convert recombinant mammalian proteins into infectious molecules,,