Changing the traditional picture of alpha-helical membrane proteins

by Kristoffer Illergård (SBC)

Wednesday 3 Dec 2008, 16:00 → 17:00 Europe/Stockholm

RB35 (RB35)

With the increasing number of available alpha-helical transmembrane (TM) protein structures, the traditional picture of membrane proteins has been challenged. First, this group of protein has been viewed as consisting of long alpha-helices connected by short loops, that together forms a bundle in the membrane. Second, it has been suggested that membrane proteins have a hydrophilic interior and a hydrophobic exterior and thus should be inside-out of globular proteins. We have performed three studies showing that this old view is incorrect. A) 7 % of the residues in the membrane core are coils. The coils are functionally conserved and frequently found within channels and transporters, where they introduce the flexibility and polarity required for transport across the membrane. B) The charged and strongly polar residues are buried and highly conserved in membrane. These residues are frequently found within channels and transporters where the polar groups often line the cavities. C) The amino acid distribution of solvent inaccessible sites is similar in membrane region as in globular region, while very different for the solvent accessible sites. This led us to develop the first accessibility-predictor that has reasonable performance in both membrane and globular regions.