title: A mammalian homolog of SEC61p and SECYp is associated with ribosomes and nascent polypeptides during translocation.
abstract: SEC61p is essential for protein translocation across the endoplasmic reticulum membrane of S. cerevisiae. We have found a mammalian homolog that shows more than 50% sequence identity with the yeast protein. Moreover, several regions of SEC61p have significant similarities with corresponding ones of SecYp of bacteria, indicating a strong evolutionary conservation of the mechanism of protein translocation. Mammalian Sec61p, like the yeast protein, is located in the immediate vicinity of nascent polypeptides during their membrane passage. It is tightly associated with membrane-bound ribosomes, suggesting that the nascent chain passes directly from the ribosome into a protein-conducting channel. These results define Sec61p as a ubiquitous key component of the protein translocation apparatus.
authors.affiliation: Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Görlich
authors.forename: S
authors.initials: S
authors.lastname: Prehn
authors.forename: E
authors.initials: E
authors.lastname: Hartmann
authors.forename: K U
authors.initials: KU
authors.lastname: Kalies
authors.forename: T A
authors.initials: TA
authors.lastname: Rapoport
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry*; D001483:Base Sequence; D001692:Biological Transport; D016384:Consensus Sequence; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D012270:Ribosomes / Q000378:metabolism*; D000069816:SEC Translocation Channels; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C057841:SecY protein, E coli