@article{199156,
  keywords = {Base Sequence, Mutation, Escherichia coli, Amino Acid Sequence, Alleles, Protein Sorting Signals, Bacterial Outer Membrane Proteins, Receptors, Virus, Porins},
  author = {Stader and Benson and Silhavy},
  title = {Kinetic analysis of lamB mutants suggests the signal sequence plays multiple roles in protein export},
  abstract = {<p>We have developed a quantitative assay to measure the rate of processing of precursor LamB into mature protein and have used this assay to characterize 10 previously isolated and 3 new lamB signal sequence mutants. The data suggest that the LamB signal sequence serves a complex function. Our assay has revealed five types of signal sequence defect: 1) a strong kinetic defect resulting from alteration of the secondary structure in the putative alpha-helical region in the hydrophobic core, 2) a strong, or 3) a weak kinetic defect due to placement of a charged residue in the hydrophobic core, 4) decreased synthesis of LamB, and 5) both a decrease in synthesis and a strong kinetic defect. The effect of an extragenic suppressor, prlA4 on the rate of processing pLamB containing signal sequence mutations was also examined and compared to the rates in wild-type strains. It was found that prlA4 increases the rate of processing in some, but not all, mutants having a kinetic defect while having no effect on the decreased synthesis seen in mutants of types 4 and 5.</p>
},
  year = {1986},
  journal = {J Biol Chem},
  volume = {261},
  pages = {15075-80},
  month = {11/1986},
  issn = {0021-9258},
  language = {eng},
}