Open AccessNascent polypeptide chains emerge from the exit domain of the large ribosomal subunit: immune mapping of the nascent chain.
Author(s) -
Carmelo Bernabéu,
James A. Lake
Publication year - 1982
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.79.10.3111
Subject(s) - ribosome , ribosomal rna , eukaryotic ribosome , protein subunit , translation (biology) , a site , ribosomal binding site , eukaryotic small ribosomal subunit , internal ribosome entry site , endoplasmic reticulum , biology , ribosomal protein , transfer rna , eukaryotic large ribosomal subunit , microbiology and biotechnology , chemistry , biochemistry , binding site , messenger rna , rna , gene
The site of the nascent polypeptide chain as it leaves the ribosome has been localized on the "exit domain" of the Escherichia coli ribosome by using IgG antibodies directed against the enzyme beta-galactosidase (EC 3.2.1.23). Thus, a functional site has been mapped on intact 70S ribosomes. The exit site is on the large subunit, approximately 70 A from the interface between subunits and nearly 150 A from the central protuberance, the likely site of peptide transfer. It is adjacent to the region corresponding to the rough endoplasmic membrane binding region of the eukaryotic ribosome but distant from ribosomal components participating in mRNA recognition and polypeptide elongation (i.e., distant from the "translational domain"). These results, together with the protease protection experiments of others, provide evidence that the nascent protein chain probably passes through the ribosome in an unfolded, fully extended conformation.