Bacteriorhodopsin Electron-crystallographic Refinement |
Part 2 (next) |
| Leu, Ile, and Val residues These residues provide most of the hydrophobic surface of the protein, the part that is in contact with membrane lipids. Leu is colored cyan, Val is colored magenta, and Ile is colored green. Notice that Leu and Val are more common than Ile. Rotate the protein for a top view and you can see that these residues also help fill up the interior of the protein. Asn and Gln residues These residues are quite rare. Asn is colored green and Gln is colored magenta. Two Asn residues are found at the N-termini of alpha-helices, 76 and 202 (at the bottom), and a third is found in the interior of an alpha-helix, 176. Gln is not found in any of the alpha-helices, which tend to be more hydrophobic. Acidic residues Acidic residues Asp and Glu are shown in cpk, Asp in pink and Glu in magenta. In addition to Asp 85 (orange) and Asp 96 (red), only Asp 115 and Asp 212 appear in the α-helical regions. Salt bridges Basic residues residues are colored blue and acidic residues are colored red. There appear to be some salt bridges on the surface, such as Glu 194 and Arg 134 (lower right). Electron-crystallographic refinement of the structure of bacteriorhodopsin. 2brd (PDB) |