Contribution of positively charged flanking residues to the insertion of transmembrane helices into the endoplasmic reticulum.
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.
Lerch-Bader
Mirjam
M
Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
Lundin
Carolina
C
Kim
Hyun
H
Nilsson
Ingmarie
I
von Heijne
Gunnar
G
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
D002412:Cations; D029968:Escherichia coli Proteins