title: The amino terminus of the aspartate chemoreceptor is formylmethionine.
abstract: The amino terminus of the Salmonella typhimurium aspartate receptor has been identified as formylmethionine by mass spectral analysis of the amino-terminal tryptic peptide. Purification and analysis of the blocked amino-terminal peptide was facilitated by the use of a mutant aspartate receptor which has a cysteine residue at position 3. The sequence of this peptide confirms the translational start site predicted from the nucleotide sequence of the tar gene. Furthermore, in vivo labeling experiments reveal that the formyl group is present on chemotaxis receptors produced at wild-type levels in Escherichia coli, indicating that the presence of the formyl group is not a consequence of over-production of the receptor. The stability of the amino-terminal formyl group on the receptor may be a consequence of the membrane localization of the receptor and the dependence of this localization on the membrane transport machinery of the cell.
authors.affiliation: Department of Biochemistry, University of California, Berkeley 94720.
authors.forename: D L
authors.initials: DL
authors.lastname: Milligan
authors.forename: D E
authors.initials: DE
authors.lastname: Koshland
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000032:analysis; D004926:Escherichia coli / Q000032:analysis; D013058:Mass Spectrometry; D008715:Methionine / Q000031:analogs & derivatives; D008969:Molecular Sequence Data; D009154:Mutation; D009239:N-Formylmethionine; D010446:Peptide Fragments / Q000302:isolation & purification; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000235:genetics; D012486:Salmonella typhimurium / Q000032:analysis*; D014357:Trypsin
chemical_list: D010446:Peptide Fragments; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; C031959:aspartic acid receptor; D009239:N-Formylmethionine; D008715:Methionine; D014357:Trypsin