Figure 5.

VICE/HINT mapping of the Sec14 and Sfh PITP lipid-binding cavities. A, VICE-calculated binding cavity of Sfh1 was mapped with HINT complementary maps, and the PtdIns (top) and PtdCho (bottom) headgroup-binding regions are illustrated. PtdIns is bound in the cavity at the interface between the LBD and tripod motifs. The inositol headgroup (1) and glycerol backbone-binding region (2) are localized in distinctive polar microenvironments of the cavity surface. The acyl chains (3) pack into the largely hydrophobic LBD. PtdCho binds the cavity at the interface between the LBD and tripod motifs. The choline headgroup (1) is located in a hydrophobic area in the near vicinity of an extensive polar region. The PtdCho phosphate moiety (2) is coordinated in a polar surface, and the acyl chains (3) pack into the largely hydrophobic LBD. The Sfh1 α-carbon backbone is rendered in ribbon style, and the lipid ligands are rendered with ball and stick. In HINT complementary maps, yellow contours identify hydrophobic regions, and blue and red contours identify polar electropositive and electronegative surfaces, respectively. B, lipid-binding cavity maps for Sec14 and the Sfh PITPs are shown. Binding cavities were mapped by the VICE cavity detection algorithm and HINT complementary maps. In HINT complementary maps, yellow contours depict hydrophobic regions, and blue and red contours identify polar electropositive and electronegative cavity surfaces, respectively.