Planta

, Volume 189, Issue 1, pp 24–29

Targeting of oleosins to the oil bodies of oilseed rape (Brassica napus L.)

  • Matthew J. Hills
  • Martin D. Watson
  • Denis J. Murphy
Article

DOI: 10.1007/BF00201339

Cite this article as:
Hills, M.J., Watson, M.D. & Murphy, D.J. Planta (1993) 189: 24. doi:10.1007/BF00201339

Abstract

Oleosins of Brassica napus L. (oilseed rape) synthesized by in-vitro translation were found to be very efficiently targeted to microsomal membranes but only poorly translocated to oil bodies or emulsified oil. The use of other bilayer membranes as controls showed that this interaction was specific. The rate of oleosin synthesis in the presence of microsomes was enhanced about threefold, indicative of the involvement of the signal-recognition particle in the targeting process. There is no evidence for the cleavage of the protein during targeting and the protein sequence reveals no consensus cleavage site for the signal peptide. Protection experiments using Proteinase K revealed that about 6 kDa of the protein is exposed on the cytoplasmic side of the ER but the remainder is protected. Carbonate (pH 11) washing of microsomal membranes after in-vitro translation confirmed that oleosins have a domain which remains inserted in the ER rather than the protein being transported completely into the lumen of the ER. These results indicate that oleosins are transported via the ER prior to their accumulation on oil bodies.

Key words

Brassica (protein targeting) Oil body Oleosin (in-vitro translation) Protein targeting 

Abbreviations

cDNA

copy DNA

SDS-PAGE

sodium dodecyl sulphate-polyacrylamide gel electrophoresis

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Matthew J. Hills
    • 1
  • Martin D. Watson
    • 2
  • Denis J. Murphy
    • 1
  1. 1.Department of Brassica and Oilseeds Research, The Cambridge Laboratory, Institute of Plant Science ResearchJohn Innes CentreNorwichUK
  2. 2.Department of Biological SciencesUniversity of DurhamDurhamUK

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