title: Contribution of positively charged flanking residues to the insertion of transmembrane helices into the endoplasmic reticulum.
abstract: Positively charged residues located near the cytoplasmic end of hydrophobic segments in membrane proteins promote membrane insertion and formation of transmembrane alpha-helices. A quantitative understanding of this effect has been lacking, however. Here, using an in vitro transcription-translation system to study the insertion of model hydrophobic segments into dog pancreatic rough microsomes, we show that a single Lys or Arg residue typically contributes approximately -0.5 kcal/mol to the apparent free energy of membrane insertion (DeltaG(app)) when placed near the cytoplasmic end of a hydrophobic segment and that stretches of 3-6 Lys residues can contribute significantly to DeltaG(app) from a distance of up to approximately 13 residues away.
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Lerch-Bader
authors.forename: Carolina
authors.initials: C
authors.lastname: Lundin
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.forename: Ingmarie
authors.initials: I
authors.lastname: Nilsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D002412:Cations / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological
chemical_list: D002412:Cations; D029968:Escherichia coli Proteins