Pushing the signal hypothesis: what are the limits?
Recent advances in understanding the in vitro translocation of nascent polypeptides across the endoplasmic reticulum (ER) membrane have established a molecular basis for the initial reactions predicted by the signal hypothesis. The first two events involve a transient arrest of nascent chain elongation, followed by a docking maneuver with the ER membrane which releases this block. It is not clear, however, that such signal sequence-mediated transfer occurs in the case of all proteins, or for that matter in all cell-free translation systems.
D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D010455:Peptides / Q000378:metabolism*; D021382:Protein Sorting Signals; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D012270:Ribosomes / Q000378:metabolism
D008565:Membrane Proteins; D010455:Peptides; D021382:Protein Sorting Signals; D011506:Proteins; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; C035026:SRPRA protein, human; C036318:signal peptide receptor