Topic
Na+/K+-ATPase
About: Na+/K+-ATPase is a research topic. Over the lifetime, 10756 publications have been published within this topic receiving 356008 citations.
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TL;DR: Afhnity for Monovalent Cations and Quantitative Relation between Effect of Na+ + K+ on Enzyme System and Active Transport in Intact Cell.
Abstract: Afhnity for Monovalent Cations. 597 Relationship of Enzyme System to ATP. 598 Isolation of Enzyme System from Other Cells with Active Transport of Na+ and K+ 602 Location of Enzyme System in the Cell. 604 Effect of Cardiac Glycosides. 605 Quantitative Relation between Effect of Na+ + K+ on Enzyme System and Active Transport in Intact Cell. 606 Nature of Enzyme System. 607 Relation of (Na + + K+)-Activated Enzyme System to Active Transport of Cations. 6 10 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6’4
1,946 citations
TL;DR: Evidence suggests that aprotein kinase complex consisting of the myristoylated calcium-binding protein SOS3 and the serine/threonine protein kinase SOS2 is activated by a salt-stress-elicited calcium signal, which phosphorylates and activates various ion transporters, such as the plasma membrane Na(+)/H(+) antiporter SOS1.
1,843 citations
TL;DR: In cardiac myocytes, and probably other cell types, the exchanger serves a housekeeping role by maintaining a low intracellular Ca2+ concentration; its possible role in cardiac excitation-contraction coupling is controversial.
Abstract: The Na+/Ca2+ exchanger, an ion transport protein, is expressed in the plasma membrane (PM) of virtually all animal cells. It extrudes Ca2+ in parallel with the PM ATP-driven Ca2+ pump. As a reversible transporter, it also mediates Ca2+ entry in parallel with various ion channels. The energy for net Ca2+ transport by the Na+/Ca2+ exchanger and its direction depend on the Na+, Ca2+, and K+ gradients across the PM, the membrane potential, and the transport stoichiometry. In most cells, three Na+ are exchanged for one Ca2+. In vertebrate photoreceptors, some neurons, and certain other cells, K+ is transported in the same direction as Ca2+, with a coupling ratio of four Na+ to one Ca2+ plus one K+. The exchanger kinetics are affected by nontransported Ca2+, Na+, protons, ATP, and diverse other modulators. Five genes that code for the exchangers have been identified in mammals: three in the Na+/Ca2+ exchanger family (NCX1, NCX2, and NCX3) and two in the Na+/Ca2+ plus K+ family (NCKX1 and NCKX2). Genes homologous to NCX1 have been identified in frog, squid, lobster, and Drosophila. In mammals, alternatively spliced variants of NCX1 have been identified; dominant expression of these variants is cell type specific, which suggests that the variations are involved in targeting and/or functional differences. In cardiac myocytes, and probably other cell types, the exchanger serves a housekeeping role by maintaining a low intracellular Ca2+ concentration; its possible role in cardiac excitation-contraction coupling is controversial. Cellular increases in Na+ concentration lead to increases in Ca2+ concentration mediated by the Na+/Ca2+ exchanger; this is important in the therapeutic action of cardiotonic steroids like digitalis. Similarly, alterations of Na+ and Ca2+ apparently modulate basolateral K+ conductance in some epithelia, signaling in some special sense organs (e.g., photoreceptors and olfactory receptors) and Ca2+-dependent secretion in neurons and in many secretory cells. The juxtaposition of PM and sarco(endo)plasmic reticulum membranes may permit the PM Na+/Ca2+ exchanger to regulate sarco(endo)plasmic reticulum Ca2+ stores and influence cellular Ca2+ signaling.
1,715 citations
TL;DR: The salt tolerance locus SOS1 from Arabidopsis has been shown to encode a putative plasma membrane Na+/H+ antiporter, and a model in which SOS1 functions in retrieving Na+ from the xylem stream under severe salt stress, whereas under mild salt stress it may function in loading Na+ into the Xylem.
Abstract: The salt tolerance locus SOS1 from Arabidopsis has been shown to encode a putative plasma membrane Na(+)/H(+) antiporter. In this study, we examined the tissue-specific pattern of gene expression as well as the Na(+) transport activity and subcellular localization of SOS1. When expressed in a yeast mutant deficient in endogenous Na(+) transporters, SOS1 was able to reduce Na(+) accumulation and improve salt tolerance of the mutant cells. Confocal imaging of a SOS1-green fluorescent protein fusion protein in transgenic Arabidopsis plants indicated that SOS1 is localized in the plasma membrane. Analysis of SOS1 promoter-beta-glucuronidase transgenic Arabidopsis plants revealed preferential expression of SOS1 in epidermal cells at the root tip and in parenchyma cells at the xylem/symplast boundary of roots, stems, and leaves. Under mild salt stress (25 mM NaCl), sos1 mutant shoot accumulated less Na(+) than did the wild-type shoot. However, under severe salt stress (100 mM NaCl), sos1 mutant plants accumulated more Na(+) than did the wild type. There also was greater Na(+) content in the xylem sap of sos1 mutant plants exposed to 100 mM NaCl. These results suggest that SOS1 is critical for controlling long-distance Na(+) transport from root to shoot. We present a model in which SOS1 functions in retrieving Na(+) from the xylem stream under severe salt stress, whereas under mild salt stress it may function in loading Na(+) into the xylem.
1,121 citations
TL;DR: The Na,K-ATPase or sodium pump carries out the coupled extrusion and uptake of Na and K ions across the plasma membranes of cells of most higher eukaryotes, and areas where there is still considerable uncertainty are highlighted.
Abstract: ▪ Abstract The Na,K-ATPase or sodium pump carries out the coupled extrusion and uptake of Na and K ions across the plasma membranes of cells of most higher eukaryotes. It is a member of the P-type ...
1,086 citations