nascent polypeptide-associated complex (NAC)

Function: 1) prevents inappropriate targeting of non-secretory polypeptides to the endoplasmic reticulum (ER) 2) binds to nascent polypeptide chains as they emerge from the ribosome & blocks their interaction with the signal recognition particle (SRP), whic targets nascent secretory peptides to the ER 3) diminishes inherent affinity of ribosomes for protein translocation sites in the ER membrane (M sites) 4) associates with ribosomes through the BTF3 subunit Structure: - consists of NACA & BTF3 (both subunits can contact nascent polypeptide chains)

General

chaperonin; chaperone molecular complex

Properties

COMPARTMENT: cytoplasm SUBUNITS: nascent polypeptide-associated complex subunit alpha COMPARTMENT: cytoplasm cell nucleus MOTIF: Ser phosphorylation site {S43} DNA-binding motif SITE: 69-80 NAC-A/B {70-135} Thr phosphorylation site {T159} Thr phosphorylation site {T161} Ser phosphorylation site {S166} UBA domain {176-213} transcription factor BTF3 COMPARTMENT: cell nucleus MOTIF: NAC-A/B {82-147}

References

- Martinus RD et al Role of chaperones in the biogenesis and maintenance of the mitochondrion. FASEB J 9:371 1995 PMID: 7896006

Components

nascent polypeptide-associated complex subunit alpha (NAC-alpha, alpha-NAC, Hom s 2.02, NACA) transcription factor BTF3; RNA polymerase B transcription factor-3 (BTF3, NACB, OK/SW-cl8)