title: A periodicity analysis of transmembrane helices.
abstract: Transmembrane helices and the helical bundles which they form are the major building blocks of membrane proteins. Since helices are characterized by a given periodicity, it is possible to search for patterns of traits which typify one side of the helix and not the other (e.g. amphipathic helices contain a polar and apolar sides). Using Fourier transformation we have analyzed solved membrane protein structures as well as sequences of membrane proteins from the Swiss-Prot database. The traits searched included aromaticity, volume and ionization. While a number of motifs were already recognized in the literature, many were not. One particular example involved helix VII of lactose permease which contains seven aromatic residues on six helical turns. Similarly six glycine residues in four consecutive helical turns were identified as forming a motif in the chloride channel. A tabulation of all the findings is presented as well as a possible rationalization of the function of the motif.
authors.affiliation: The Alexander Silberman Institute of Life Sciences, Department of Biological Chemistry, The Hebrew University, Givat-Ram, Jerusalem 91904, Israel.
authors.forename: Hadas
authors.initials: H
authors.lastname: Leonov
authors.forename: Isaiah T
authors.initials: IT
authors.lastname: Arkin
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D003198:Computer Simulation; D005583:Fourier Analysis; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010507:Periodicity; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment / Q000379:methods*; D020539:Sequence Analysis, Protein / Q000379:methods*
chemical_list: D008565:Membrane Proteins