Charge pair interactions in a model transmembrane helix in the ER membrane

We have examined the effects of Lys-Asp charge pair interactions on the pos ition of a model poly-Leu transmembrane helix in the ER membrane using the so-called "glycosylation mapping" technique. Based on an analysis of a set of constructs containing pairs of positively charged Lys and negatively cha rged Asp residues in various positions in the model helix, we show that the helix is located deeper in the membrane when Lys and Asp are placed one he lical turn apart than for other spacings of the two residues. These results suggest that salt-bridge formation between residues located on the same fa ce of a transmembrane helix may reduce the free energy of membrane partitio ning. (C) 2000 Academic Press.