Nascent polypeptide-associated complex in Drosophila melanogaster

The nascent polypeptide-associated complex (NAC) is a heterodimer of an alpha and a beta subunit that binds near the exit tunnel of translating ribosomes and contacts emerging nascent chains. It acts as a ribosome-associated chaperone and sorting factor that shields nascent polypeptides and regulates their access to the signal recognition particle and to other targeting pathways. Drosophila has two alpha-subunit genes (Nacalpha and gNacalpha) and an expanded family of beta-subunit (BTF3-like) genes: bicaudal (bic), uncNacbeta and a cluster of betaNACtes genes, the latter expressed in the male germline.

Parts follow FlyBase subgroups NACA and NACB. Which alpha and beta paralogs pair in vivo, and in which tissues, is not resolved for most combinations; the variants record the paralogs available for each subunit position. The betaNACtes genes are grouped as one variant because they are near-identical testis-expressed copies. No molecular function is assigned: NAC binds ribosomes at the exit tunnel and emerging nascent chains, and its subunits carry only ribosome binding terms in GOA. FlyBase groups realized by this module: NACS (FBgg0001786). Subgroups folded into it: NACA, NACB. Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_nascent_polypeptide_associated_complex.yaml. None of the member genes has a gene review in this repository yet.