title: The Sec62-Sec63 translocon facilitates translocation of the C-terminus of membrane proteins.
abstract: The Sec62-Sec63 complex mediates post-translational translocation of a subset of primarily secretory proteins into the endoplasmic reticulum (ER) in yeast. Therefore, it has been thought that membrane proteins, which are mainly co-translationally targeted into the ER, are not handled by the Sec62-Sec63 translocon. By systematic analysis of single and multi-spanning membrane proteins with broad sequence context [with differing hydrophobicity, flanking charged residues and orientation of transmembrane (TM) segments], we show that mutations in the N-terminal cytosolic domain of yeast Sec62 impair its interaction with Sec63 and lead to defects in membrane insertion and translocation of the C-terminus of membrane proteins. These results suggest that there is an unappreciated function of the Sec62-Sec63 translocon in regulating topogenesis of membrane proteins in the eukaryotic cell.
authors.affiliation: School of Biological Sciences, Seoul National University, Seoul 151-747, South Korea.
authors.forename: Sung-jun
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: School of Biological Sciences, Seoul National University, Seoul 151-747, South Korea.
authors.forename: Ji Eun Hani
authors.initials: JE
authors.lastname: Kim
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Reithinger
authors.affiliation: School of Biological Sciences, Seoul National University, Seoul 151-747, South Korea joy@snu.ac.kr.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D018988:Bacterial Translocation; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D021381:Protein Transport; D000069816:SEC Translocation Channels; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels
keywords: Co-translational translocation; ER; Endoplasmic reticulum; Sec61; Topology; Yeast