The nascent polypeptide-associated complex (NAC), consisting of alpha and beta subunits, is an essential ribosome-associated protein conserved in eukaryotes. It is a ubiquitously expressed co-translational regulator of nascent protein folding and sorting. Drosophila species, at least, have two alpha subunit paralogs - one is expressed ubiquitously and the other is expressed specifically in the germline. (Adapted from
FBrf0253862.)