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Synthesis of the major oil-body membrane protein in developing rapeseed (Brassica napus) embryos. Integration with storage-lipid and storage-protein synthesis and implications for the mechanism of oil-body formation.
Biochem J. 1989 Feb 15; 258(1):285-93.BJ

Abstract

The synthesis of the major protein and lipid storage reserves during embryogenesis in oilseed rape (Brassica napus L., cv. Mikado) has been examined by biochemical, immunological and immunocytochemical techniques. The mature seeds contained about 45% (w/w) storage oil and 25% (w/w) protein. There were three major seed protein components, i.e. about 40-50% total protein was cruciferin, 20% was napin and 20% was a 18 kDa hydrophobic polypeptide associated with the proteinaceous membrane surrounding the storage oil bodies. Embryogenesis was divided into four overlapping stages with regard to the synthesis of these storage components: (1) for the first 3 weeks after flowering, little, if any, synthesis of storage components was observed; (2) storage-oil synthesis began at about week 3, and maximal rates were from weeks 4 to 7; (3) synthesis of the soluble storage proteins cruciferin and napin started at week 6 and rates were maximal between weeks 8 and 11; (4) the final stage was the synthesis of the 19 kDa oil-body polypeptide, which started at weeks 8-10 and was at a maximal rate between weeks 10 and 12. The synthesis of the 19 kDa oil-body protein therefore occurred independently of the synthesis of the soluble seed storage proteins. This former synthesis did not occur until shortly before the insertion of the 19 kDa polypeptide into the oil-body membrane. No evidence was found, either from sucrose-density-gradient-centrifugation experiments or from immunogold-labelling studies, for its prior accumulation in the endoplasmic reticulum. Conventional and immunogold-electron-microscopic studies showed that oil bodies were synthesized in the early to middle stages of seed development without a strongly electron-dense membrane. Such a membrane was only found at later stages of seed development, concomitantly with the synthesis of the 19 kDa protein. It is proposed that, in rapeseed embryos, oil bodies are initially formed with no proteinaceous membrane. Such a membrane is formed later in development after insertion by ribosomes of the hydrophobic 19 kDa polypeptide directly into the oil bodies.

Authors+Show Affiliations

Department of Biological Sciences, University of Durham, U.K.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

2930514

Citation

Murphy, D J., et al. "Synthesis of the Major Oil-body Membrane Protein in Developing Rapeseed (Brassica Napus) Embryos. Integration With Storage-lipid and Storage-protein Synthesis and Implications for the Mechanism of Oil-body Formation." The Biochemical Journal, vol. 258, no. 1, 1989, pp. 285-93.
Murphy DJ, Cummins I, Kang AS. Synthesis of the major oil-body membrane protein in developing rapeseed (Brassica napus) embryos. Integration with storage-lipid and storage-protein synthesis and implications for the mechanism of oil-body formation. Biochem J. 1989;258(1):285-93.
Murphy, D. J., Cummins, I., & Kang, A. S. (1989). Synthesis of the major oil-body membrane protein in developing rapeseed (Brassica napus) embryos. Integration with storage-lipid and storage-protein synthesis and implications for the mechanism of oil-body formation. The Biochemical Journal, 258(1), 285-93.
Murphy DJ, Cummins I, Kang AS. Synthesis of the Major Oil-body Membrane Protein in Developing Rapeseed (Brassica Napus) Embryos. Integration With Storage-lipid and Storage-protein Synthesis and Implications for the Mechanism of Oil-body Formation. Biochem J. 1989 Feb 15;258(1):285-93. PubMed PMID: 2930514.
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TY - JOUR T1 - Synthesis of the major oil-body membrane protein in developing rapeseed (Brassica napus) embryos. Integration with storage-lipid and storage-protein synthesis and implications for the mechanism of oil-body formation. AU - Murphy,D J, AU - Cummins,I, AU - Kang,A S, PY - 1989/2/15/pubmed PY - 1989/2/15/medline PY - 1989/2/15/entrez SP - 285 EP - 93 JF - The Biochemical journal JO - Biochem J VL - 258 IS - 1 N2 - The synthesis of the major protein and lipid storage reserves during embryogenesis in oilseed rape (Brassica napus L., cv. Mikado) has been examined by biochemical, immunological and immunocytochemical techniques. The mature seeds contained about 45% (w/w) storage oil and 25% (w/w) protein. There were three major seed protein components, i.e. about 40-50% total protein was cruciferin, 20% was napin and 20% was a 18 kDa hydrophobic polypeptide associated with the proteinaceous membrane surrounding the storage oil bodies. Embryogenesis was divided into four overlapping stages with regard to the synthesis of these storage components: (1) for the first 3 weeks after flowering, little, if any, synthesis of storage components was observed; (2) storage-oil synthesis began at about week 3, and maximal rates were from weeks 4 to 7; (3) synthesis of the soluble storage proteins cruciferin and napin started at week 6 and rates were maximal between weeks 8 and 11; (4) the final stage was the synthesis of the 19 kDa oil-body polypeptide, which started at weeks 8-10 and was at a maximal rate between weeks 10 and 12. The synthesis of the 19 kDa oil-body protein therefore occurred independently of the synthesis of the soluble seed storage proteins. This former synthesis did not occur until shortly before the insertion of the 19 kDa polypeptide into the oil-body membrane. No evidence was found, either from sucrose-density-gradient-centrifugation experiments or from immunogold-labelling studies, for its prior accumulation in the endoplasmic reticulum. Conventional and immunogold-electron-microscopic studies showed that oil bodies were synthesized in the early to middle stages of seed development without a strongly electron-dense membrane. Such a membrane was only found at later stages of seed development, concomitantly with the synthesis of the 19 kDa protein. It is proposed that, in rapeseed embryos, oil bodies are initially formed with no proteinaceous membrane. Such a membrane is formed later in development after insertion by ribosomes of the hydrophobic 19 kDa polypeptide directly into the oil bodies. SN - 0264-6021 UR - https://www.unboundmedicine.com/medline/citation/2930514/Synthesis_of_the_major_oil_body_membrane_protein_in_developing_rapeseed__Brassica_napus__embryos__Integration_with_storage_lipid_and_storage_protein_synthesis_and_implications_for_the_mechanism_of_oil_body_formation_ L2 - https://portlandpress.com/biochemj/article-lookup/doi/10.1042/bj2580285 DB - PRIME DP - Unbound Medicine ER -