>TIGR00264 TIGR00264 alpha-NAC homolog; InterPro: IPR005231 Eukaryotic NAC, an abundant heterodimer composed of two homologous subunits, reversibly binds eukaryotic ribosomes and is located in direct proximity to nascent polypeptides as they emerge from the ribosome . Despite being implicated in diverse cellular functions, its role in vivo is still not completely understood. It is thought that NAC may function as a shield protecting the nascent chain from inappropriate interactions with cytosolic factors, and could regulate further translation of the polypeptide through its interaction with the ribosome. Archaeal NAC is a homodimer which appears to be functionally analogous to the eukaryotic form, associating with ribosomes and contacting the nascent polypeptide chain emerging on the ribosome . It has two domains; the NAC domain, which it shares with eukaryotic NAC, and a C-terminal UBA domain also found on the alpha, but not beta, subunit of eukaryotic NAC. The NAC domain forms a six-stranded beta-barrel structure which shows some similarities to the OB fold. This domain appears to be responsible for dimerisation, nucleic acid binding, and nascent polypeptide binding. The UBA domain is typical of ubiquitin or polyubquitin-binding proteins; its physiological role is unclear but it was suggested that it may compete with the proteosome for ubiquitin, thus inhibiting ubiquitin-mediated protein degradation. .

Probab=95.76  E-value=0.014  Score=37.97  Aligned_cols=40  Identities=25%  Similarity=0.250  Sum_probs=37.1

Q ss_pred             CCCHHHHHHHHHHHCCCHHHHHHHHHHCCCCHHHHHHHHH
Q ss_conf             3558999999987199989999999962999899999999
Q gi|254780778|r    3 KVSAVAVKELRGKTGAGIMDCKNALLEAKGDSELAIDILR   42 (296)
Q Consensus         3 ~it~~~iK~LR~~Tgag~~dCKkAL~e~~gD~e~Ai~~LR   42 (296)
T Consensus        85 eI~EdDieLvm~Q~nvs~E~ArrALeE~gGDlAEAimkL~  124 (125)
T TIGR00264        85 EISEDDIELVMEQANVSKEEARRALEEAGGDLAEAIMKLE  124 (125)
T ss_pred             ECCHHHHHHHHHHCCCCHHHHHHHHHHCCCHHHHHHHHHC
T ss_conf             4075579999976599988989998631851888987505