NACA Full-Length MS Protein Standard (NP_005585), Labeled with [U- 13C6, 15N4]-L-Arginine and [U- 13C6, 15N2]-L-Lysine, was produced in human 293 cells (HEK293) with fully chemically defined cell culture medium to obtain incorporation efficiency at Creative-Proteomics. The protein encoded by this gene associates with basic transcription factor 3 (BTF3) to form the nascent polypeptide-associated complex (NAC). NAC binds to nascent proteins as they emerge from the ribosome, blocking interaction with the signal recognition particle (SRP) and preventing mistranslocation to the endoplasmic reticulum. However, nascent proteins with an exposed signal peptide will not be bound by the encoded protein, enabling them to bind the SRP and enter the secretory pathway. This protein has been determined to be an IgE autoantigen in atopic dermatitis patients. Several transcript variants encoding two different isoforms have been found for this gene.