Functional characterization of bacterial signal peptide OmpA in a baculovirus-mediated expression system

Toshihiro Nagamine, Yu Kawasaki, Tetsutaro Iizuka, Keiju Okano, Shogo Matsumoto, Prabhakara V Choudary

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Signal sequences are evolutionarily conserved and are often functionally interchangeable between prokaryotes and eukaryotes. However, we have found that the bacterial signal peptide, OmpA, functions incompletely in insect cells. Upon baculovirus-mediated expression of chloramphenicol acetyltransferase (CAT) in insect cells, OmpA signal peptide led to the cytosolic accumulation of the CAT molecules in an aglycosylated, signal-peptide cleaved form, in addition to the secretion of the glycosylated CAT. When green fluorescent protein (GFP) was used as another reporter, the GFP molecules expressed from the OmpA-GFP construct was distributed primarily in the cytosol as aggresome-like structures. These results together suggest that, subsequent to the cleavage of OmpA signal peptide in the ER, some of the processed proteins are returned to the cytoplasm. Since the prototypical insect signal peptide, melittin, did not result in this ER-to-cytosol dislocation of the reporter proteins, we proposed a model explaining the dislocation process in insect cells, apparently selective to the OmpA-directed secretory pathway bypassing the co-translational transport.

Original languageEnglish (US)
Pages (from-to)131-142
Number of pages12
JournalCell Structure and Function
Issue number2
StatePublished - Apr 2003


  • Aggresome
  • Baculovirus
  • ER dislocation
  • Post-translational transport
  • Signal peptide

ASJC Scopus subject areas

  • Physiology
  • Structural Biology
  • Cell Biology


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