title: On the physical basis for the cis-positive rule describing protein orientation in biological membranes.
abstract: The topology of hydrophobic intramembrane proteins is characterized by a statistical asymmetry in the distribution of positively-charged residues on the two sides of the membrane, the 'inside- or cis-positive rule'. A mechanism is proposed involving only neutral residue transfer. For a tightly bound polypeptide adsorbed on the membrane and not at equilibrium, the pK values of the ionic residues related to dissociation of the proton into the aqueous phase bulk are increased because of interaction with the negative charges at the membrane surface. The pK shift would selectively neutralize aspartate and glutamate residues, favoring their translocation across the membrane, while stabilizing the impermeant positively charged state of lysine and arginine residues.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA.
authors.forename: L I
authors.initials: LI
authors.lastname: Krishtalik
authors.forename: W A
authors.initials: WA
authors.lastname: Cramer
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D017510:Protein Folding
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins