Deposition of storage proteins
1Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, Germany.
Plant Molecular Biology
|September 17, 1998
Summary
Plants store amino acids as storage proteins in specialized organelles called protein bodies. These proteins are protected from degradation through mechanisms like targeting to protein storage vacuoles (PSV) and endoplasmic reticulum-derived protein bodies (PB).
Area of Science:
- Plant biology
- Molecular biology
- Biochemistry
Background:
- Plants accumulate amino acids in storage proteins for later use.
- Storage proteins are deposited in various organs like seeds and tubers.
- Protein bodies (PB) protect storage proteins from premature degradation.
Purpose of the Study:
- To elucidate the mechanisms of storage protein deposition and targeting in plants.
- To understand the role of organelles like the endoplasmic reticulum (ER) and Golgi apparatus in protein sorting.
- To identify the targeting signals and pathways involved in protein body formation.
Main Methods:
- Analysis of storage protein biosynthesis and post-translational modifications.
- Investigating protein transport pathways from the ER to protein storage vacuoles (PSV) and protein bodies (PB).
- Identifying signal peptides and targeting sequences responsible for protein sorting.
Main Results:
- Storage proteins are synthesized on ER-bound polysomes and targeted to the ER lumen via N-terminal signal peptides.
- Proteins undergo folding, glycosylation, and disulfide bond formation within the ER.
- Proteins are transported via the Golgi apparatus to PSVs or directly to ER-derived PBs, with specific targeting signals or aggregation mediating sorting.
Conclusions:
- Storage protein targeting and deposition involve complex pathways originating in the ER.
- Both signal peptides and internal targeting sequences, as well as aggregation, play roles in directing proteins to PBs or PSVs.
- Understanding these mechanisms is crucial for plant development and nutrient storage.
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