Abstract
Many organisms adapted to live at subzero temperatures express antifreeze proteins that improve their tolerance to freezing. Although structurally diverse, all antifreeze proteins interact with ice surfaces, depress the freezing temperature of aqueous solutions, and inhibit ice crystal growth. A protein purified from carrot shares these functional features with antifreeze proteins of fish. Expression of the carrot complementary DNA in tobacco resulted in the accumulation of antifreeze activity in the apoplast of plants grown at greenhouse temperatures. The sequence of carrot antifreeze protein is similar to that of polygalacturonase inhibitor proteins and contains leucine-rich repeats.
MeSH terms
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Amino Acid Sequence
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Antifreeze Proteins
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Cloning, Molecular
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Crystallization
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DNA, Complementary
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Daucus carota / chemistry*
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Daucus carota / physiology
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Glycoproteins / chemistry*
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Glycoproteins / genetics
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Glycoproteins / isolation & purification
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Glycoproteins / physiology*
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Glycosylation
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Ice*
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Isoelectric Point
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Leucine / chemistry
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Membrane Proteins / chemistry*
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Membrane Proteins / isolation & purification
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Membrane Proteins / metabolism
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Membrane Proteins / physiology*
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Molecular Sequence Data
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Molecular Weight
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Nicotiana
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Plant Proteins / chemistry*
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Plant Proteins / genetics
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Plant Proteins / isolation & purification
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Plant Proteins / physiology*
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Plant Roots / chemistry
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Plants, Genetically Modified
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Plants, Toxic
Substances
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AFP protein, Daucus carota
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Antifreeze Proteins
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DNA, Complementary
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Glycoproteins
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Ice
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Membrane Proteins
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Plant Proteins
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Leucine