Immunolocalization of a novel annexin-like protein encoded by a stress and abscisic acid responsive gene in alfalfa.
We report here on the isolation and characterization of a full-length cDNA clone from alfalfa termed AnnMs2 encoding a 333 amino acid long polypeptide that shows 32-37% sequence identity with both mammalian and plant annexins, and has four tandem repeats. While other plant annexins exhibit a high level of sequence similarity to each other (up to 77% identity at amino acid level), AnnMs2 appears to be a distinct type of plant annexins. All the four endonexin folds contain the conserved eukaryotic motif within this alfalfa protein, but this element is considerably different in the second repeat. The AnnMs2 gene is expressed in various tissues of alfalfa with elevated mRNA accumulation in root and flower. This gene is activated in cells or tissues exposed to osmotic stress, abscisic acid (ABA) or water deficiency. The recombinant AnnMs2 protein is able to bind to phospholipid in the presence of Ca2+. Indirect immunofluorescence studies using affinity purified rabbit anti-AnnMs2 peptide antibody show mainly nucleolar localization, but the protein sequence lacks the usual nuclear localization signal. The potential role of this novel annexin-like protein in the basic and stress-induced cellular functions is discussed.
Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary. kovacs@everx.szbk.u-szeged.hu
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D000040:Abscisic Acid / Q000494:pharmacology / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D017302:Annexins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D000906:Antibodies; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017124:Conserved Sequence; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008322:Mammals; D000455:Medicago sativa / Q000235:genetics / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010940:Plant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
C114564:AnnMs2 protein, Medicago sativa; D017302:Annexins; D000906:Antibodies; D018076:DNA, Complementary; D010940:Plant Proteins; D000040:Abscisic Acid