Nascent-polypeptide-associated complex.
Nascent-polypeptide-associated complex (NAC) is a heterodimeric complex which can reversibly bind to eukaryotic ribosomes. NAC is located in direct proximity to newly synthesized polypeptide chains as they emerge from the ribosome. Although its function is thought to be conserved from yeast to humans our current knowledge about what NAC actually does in a living cell is incomplete. It has been suggested that NAC is a (i) dynamic component of the ribosomal exit tunnel, providing a shield for nascent polypeptides, (ii) negative regulator of translocation into the endoplasmic reticulum and (iii) positive regulator of translocation into the mitochondria. However, none of these hypotheses is generally accepted. Moreover, the individual subunits of NAC have been implicated in processes related to transcription rather than translation, and it is currently under debate whether NAC might be a protein of dual function. This review attempts to summarize the data from different fields and to discuss the partly controversial results in a common context.
Rospert
S
S
Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle, Germany. rospert@enzyme-halle.mpg.de
Dubaquié
Y
Y
Gautschi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D005786:Gene Expression Regulation; D006801:Humans; D008322:Mammals; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D021381:Protein Transport; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D018271:Signal Recognition Particle / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D018832:Molecular Chaperones; D018271:Signal Recognition Particle; D015534:Trans-Activators; C096099:nascent-polypeptide-associated complex