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Caleosins: Ca2+-binding proteins associated with lipid bodies.
H Naested1, G I Frandsen, G Y Jauh
1Institute of Molecular Biology, Oester Farimagsgade 2A, Copenhagen, Denmark.
Plant Molecular Biology
|February 24, 2001
Summary
Researchers discovered caleosins (CLO), a novel multigene family in plants and fungi. Caleosin AtClo1 is highly expressed in developing embryos and seeds, functioning as a lipid body protein.
Area of Science:
- Plant Molecular Biology
- Lipid Metabolism
- Protein Biochemistry
Background:
- A rice gene encoding a 27 kDa protein with a Ca2+-binding EF-hand and membrane anchor was previously identified.
- Similar genes, termed caleosins (CLO), exist in other plants and fungi.
Purpose of the Study:
- To characterize the caleosin multigene family in Arabidopsis.
- To investigate the expression patterns and localization of caleosin proteins.
Main Methods:
- Northern hybridization to analyze mRNA levels of Arabidopsis caleosin genes (AtClo1-5).
- Analysis of transgenic Arabidopsis plants using GUS reporter assays under the AtClo1 promoter.
- Immunodetection of caleosin proteins in cellular fractions of Arabidopsis and rapeseed using specific antibodies.
Main Results:
- Arabidopsis contains at least five caleosin genes (AtClo1-5).
- AtClo1 mRNA levels are high in developing embryos and mature seeds, while AtClo2-4 mRNA levels are low in various tissues.
- AtClo1 expression is strong in developing embryos and root tip cells.
- Caleosins are identified as lipid body proteins, potentially associated with an ER subdomain.
Conclusions:
- Caleosins represent a novel class of plant and fungal proteins.
- The AtClo1 gene plays a significant role in plant reproductive development, particularly in seeds.
- Caleosins are localized to lipid bodies and may have roles in lipid metabolism or membrane association.