title: The major proteins of the Escherichia coli outer cell-envelope membrane. Cyanogen bromide fragments of protein I, composition and order.
abstract: The cyanogen bromide fragments of protein I, a major protein of the Escherichia coli outer cell envelope membrane, have been isolated and characterized. There appear to be two methionine-serine or methionine-threonine sequences causing incomplete cleavage but complete conversion of methionine to homoserine. Largely due to the existence of these overlapping fragments the order of 5 of the 6 fragments present could be deduced. None of the fragments exhibits any remarkable low degree of polarity, and the tryptic fingerprint of the largest fragment (comprising about 60% of protein I) also does not show any conspicuous large fraction of lipophilic peptides. It is concluded that the domain of protein I that may be buried in the lipid phase of the outer membrane in all likelihood is not very large, and there is, in fact, no definite proof yet that protein I is a membrane protein sensu stricto.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis*; D002462:Cell Membrane / Q000032:analysis*; D003488:Cyanogen Bromide; D004926:Escherichia coli / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D010446:Peptide Fragments; D014357:Trypsin; D003488:Cyanogen Bromide