Abscisic Acid Transport in Human Erythrocytes |
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Authors: | Tiziana Vigliarolo Lucrezia Guida Enrico Millo Chiara Fresia Emilia Turco Antonio De Flora Elena Zocchi |
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Affiliation: | From the ‡Department of Experimental Medicine, Section of Biochemistry, and ;the §Center of Excellence for Biomedical Research, University of Genova, Genova 16132, Italy and ;the ¶Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino 10126, Italy |
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Abstract: | Abscisic acid (ABA) is a plant hormone involved in the response to environmental stress. Recently, ABA has been shown to be present and active also in mammals, where it stimulates the functional activity of innate immune cells, of mesenchymal and hemopoietic stem cells, and insulin-releasing pancreatic β-cells. LANCL2, the ABA receptor in mammalian cells, is a peripheral membrane protein that localizes at the intracellular side of the plasma membrane. Here we investigated the mechanism enabling ABA transport across the plasmamembrane of human red blood cells (RBC). Both influx and efflux of [3H]ABA occur across intact RBC, as detected by radiometric and chromatographic methods. ABA binds specifically to Band 3 (the RBC anion transporter), as determined by labeling of RBC membranes with biotinylated ABA. Proteoliposomes reconstituted with human purified Band 3 transport [3H]ABA and [35S]sulfate, and ABA transport is sensitive to the specific Band 3 inhibitor 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid. Once inside RBC, ABA stimulates ATP release through the LANCL2-mediated activation of adenylate cyclase. As ATP released from RBC is known to exert a vasodilator response, these results suggest a role for plasma ABA in the regulation of vascular tone. |
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Keywords: | abscisic acid (ABA) ATP cyclic AMP (cAMP) liposome membrane transporter reconstitution RBC Band 3 ATP-release |
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