InterPro domain: IPR038187

In eukaryotes, the Nascent polypeptide-Associated Complex (NAC) is a heterodimeric cytosolic protein complex composed of NAC alpha (NACA) and NAC beta (BTF3) [ 1 ]. NAC binds reversibly to the ribosome where it is in contact with nascent chains as they emerge from the ribosome. But the cellular function of NAC seems to be much more diverse as it is also involved in transcription regulation and mitochondrial translocation [ 2 , 3 ]. Alpha and beta NACs share homology with each other, both contain a NAC A/B domain. In archaea no beta NAC proteins are found; the complex is an homodimer of NAC alpha [ 4 , 5 ].

The crystal structure of an archeal NAC has been solved [ 6 ]. The NAC A/B domain consists of six strands arranged in a beta barrel structure similar to the OB fold. Various OB folds interact with ribosomal RNA which could suggest a similar role for the NAC A/B domain.

1. Crystal structures of NAC domains of human nascent polypeptide-associated complex (NAC) and its αNAC subunit. Protein Cell 1, 406-16
2. Nascent-polypeptide-associated complex. Cell. Mol. Life Sci. 59, 1632-9
3. The crystal structure of the human nascent polypeptide-associated complex domain reveals a nucleic acid-binding region on the NACA subunit . Biochemistry 49, 2890-6
4. Comparative genomics of the Archaea (Euryarchaeota): evolution of conserved protein families, the stable core, and the variable shell. Genome Res. 9, 608-28
5. The crystal structure of archaeal nascent polypeptide-associated complex (NAC) reveals a unique fold and the presence of a ubiquitin-associated domain. J. Biol. Chem. 280, 15849-54