title: The 3'-terminal half of the btuB gene of Citrobacter freundii defines essential residues and supports a topological model for the outer membrane receptor.
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D016971:Citrobacter freundii / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018000:Receptors, Peptide / Q000235:genetics; D014805:Vitamin B 12 / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; C044592:BtuB protein, E coli; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D018000:Receptors, Peptide; D014805:Vitamin B 12