title: Proline kinks in transmembrane alpha-helices.
abstract: Integral membrane proteins often contain proline residues in their presumably alpha-helical transmembrane segments. This is in marked contrast to globular proteins, where proline is rarely found inside alpha-helices. Proline residues cause kinks in helices, and, in addition to leaving the i-4 backbone carbonyl without its normal hydrogen bond donor, also sterically prevent the (i-3)-carbonyl-(i + l)-amide backbone hydrogen bond from forming. Here, some structural aspects of proline kinks in transmembrane helices are discussed on the basis of an analysis of Pro-kinked helices in the photosynthetic reaction center and bacteriorhodopsin, as well as results from an analysis of Pro-containing transmembrane segments identified in the NBRF Protein Sequence Databank.
authors.affiliation: Department of Molecular Biology, Karolinska Institute Center for Biotechnology, Huddinge, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D000595:Amino Acid Sequence; D001436:Bacteriorhodopsins / Q000737:chemistry*; D006860:Hydrogen Bonding; D008565:Membrane Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D001436:Bacteriorhodopsins; D011392:Proline