title: Primary structure of major outer membrane protein II (ompA protein) of Escherichia coli K-12.
abstract: The amino acid sequence of major outer membrane protein II (ompA protein) from Escherichia coli K-12 has been determined. The transmembrane polypeptide consists of 325 residues, resulting in a molecular weight of 35,159. The transmembrane part of the protein is located between residues 1 and 177. In this part of the protein a predominantly lipophilic 27-residue segment exists that perhaps spans the membrane in a mostly alpha-helical conformation, or a 19-residue stretch of this segment might traverse the membrane linearly. Inside the outer membrane a sequence -Ala-Pro-Ala-Pro-Ala-Pro-Ala-Pro- exists that, analogous to the -Cys-Pro-Pro-Cys-Pro- sequence in the hinge region of immunoglobulin, could assume the conformation of a polyproline helix. Computer analysis did not reveal a clear overall pattern of internal homology in the protein; besides the -Ala-Pro- repeat, only one local area (two adjacent dodecapeptide segments) shows some repetitiveness. The same analysis did not produce evidence for internal homology in the previously determined sequence of outer membrane protein I (porin) nor was any marked resemblance detected between transmembrane proteins I and II.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000648:ultrastructure*; D008565:Membrane Proteins / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D011487:Protein Conformation
chemical_list: D000596:Amino Acids; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C078167:OMPA outer membrane proteins