InterPro domain: IPR039370

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.

This entry represents the mammalian transcription factor BTF3, which is a component of the nascent polypeptide-associated complex (NAC) [ 6 ]. In yeast, this component is known as nascent polypeptide-associated complex subunit beta-1 (or EGD1) [ 7 ].

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
6. The alpha and beta subunit of the nascent polypeptide-associated complex have distinct functions. J. Biol. Chem. 275, 37838-45
7. Initial characterization of the nascent polypeptide-associated complex in yeast. Yeast 15, 397-407