title: Nascent polypeptide chains exit the ribosome in the same relative position in both eucaryotes and procaryotes.
abstract: We located the polypeptide nascent chain as it leaves cytoplasmic ribosomes from the plant Lemna gibba by immune electron microscopy using antibodies against the small subunit of the enzyme ribulose-1,5-bisphosphate carboxylase. Similar studies with Escherichia coli ribosomes, using antibodies directed against the enzyme beta-galactosidase, show that the polypeptide nascent chain emerges in the same relative position in plants and bacteria. The eucaryotic ribosomal exit site is on the large subunit, approximately 75 A from the interface between subunits and nearly 160 A from the central protuberance, the presumed site for peptidyl transfer. This is the first functional site on both the eucaryotic and procaryotic ribosomes to be determined.
mesh_terms: D004926:Escherichia coli / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism; D007158:Immunologic Techniques; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D010455:Peptides / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000276:immunology
chemical_list: D007074:Immunoglobulin G; D046911:Macromolecular Substances; D010455:Peptides; D012273:Ribulose-Bisphosphate Carboxylase