Orientation and structure of SHP in lipid bilayers.

<p>(<b>a</b>) The depth of peptide penetration into the hydrocarbon region of model liposomes was determined via parallax analysis. Assuming a hydrocarbon bilayer thickness of 29 Å, the depths of tryptophans spanning SHP-1 (blue •) and SHP-3 (red ▪) are plotted against a background of the outer leaflet of a POPC bilayer. (<b>b</b>) Circular dichroism spectroscopy of SHP-1 in aqueous buffer (green •) and in the presence of egg phosphatidylcholine liposomes (blue •). (<b>c</b>) Molecular dynamic modeling of SHP-1 in a lipid environment. The backbone trace (top) illustrates a predominantly α-helical structure with disordered termini and an internal disordered region. Surface potential representations (N to C terminal, middle; C to N terminal, bottom) indicate positively charged patches (blue) formed by the N-terminal amino acid and the arginine at position 14. Non-polar and negatively charged regions are shown in white and red, respectively.