scholarly journals Na+/H+ Exchange Activity in the Plasma Membrane of Arabidopsis

2003 ◽  
Vol 132 (2) ◽  
pp. 1041-1052 ◽  
Author(s):  
Quan-Sheng Qiu ◽  
Bronwyn J. Barkla ◽  
Rosario Vera-Estrella ◽  
Jian-Kang Zhu ◽  
Karen S. Schumaker
Keyword(s):  
Plasma Membrane ◽  
Exchange Activity

Ca2+ Clearance at Growth Cones Produced by Crayfish Motor Axons in an Explant Culture

2003 ◽  
Vol 89 (6) ◽  
pp. 3225-3234 ◽  
Author(s):  
Nidhi Rumpal ◽  
Gregory A. Lnenicka
Keyword(s):  
Plasma Membrane ◽  
Growth Cones ◽  
Explant Culture ◽  
Motor Axons ◽  
Rapid Decay ◽  
Mitochondrial Inhibitors ◽  
High K ◽  
Explant Cultures ◽  
Regulation Of Growth ◽  
Exchange Activity

Intracellular free Ca2+ concentration ([Ca2+]i) plays an important role in the regulation of growth cone (GC) motility; however, the mechanisms responsible for clearing Ca2+ from GCs have not been examined. We studied the Ca2+-clearance mechanisms in GCs produced by crayfish tonic and phasic motor axons by measuring the decay of [Ca2+]i after a high [K+] depolarizing pulse using fura-2AM. Tonic motor axons regenerating in explant cultures develop GCs with more rapid Ca2+ clearance than GCs from phasic axons. When Na/Ca exchange was blocked by replacing external Na+ with N-methyl-d-glucamine (NMG), [Ca2+]i decay was delayed in both tonic and phasic GCs. Tonic GCs appear to have higher Na/Ca exchange activity than phasic ones since reversal of Na/Ca exchange by lowering external Na+ caused a greater increase in [Ca2+]i for tonic than phasic GCs. Application of the mitochondrial inhibitors, Antimycin A1 (1 μM) and CCCP (10 μM), demonstrated that mitochondrial Ca2+ uptake/release was more prominent in phasic than tonic GCs. When both Na/Ca exchange and mitochondria were inhibited, the plasma membrane Ca2+ ATPase was effective in extruding Ca2+ from tonic, but not phasic GCs. We conclude that Na/Ca exchange plays a prominent role in extruding large Ca2+ loads from both tonic and phasic GCs. High Na/Ca exchange activity in tonic GCs contributes to the rapid decay of [Ca2+]i in these GCs; low rates of Ca2+ extrusion plus the release of Ca2+ from mitochondria prolongs the decay of [Ca2+]i in the phasic GCs.

scholarly journals One of the origins of plasma membrane phosphatidylserine in plant cells is a local synthesis by a serine exchange activity

FEBS Letters ◽  
1999 ◽  
Vol 464 (1-2) ◽  
pp. 80-84 ◽  
Author(s):  
Patrick Vincent ◽  
Lilly Maneta-Peyret ◽  
Bénédicte Sturbois-Balcerzak ◽  
Michel Duvert ◽  
Claude Cassagne ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Plant Cells ◽  
Local Synthesis ◽  
Exchange Activity

Ca2+ Clearance at Growth Cones Produced by Crayfish Motor Axons in an Explant Culture

2003 ◽  
Vol 89 (6) ◽  
pp. 3225-3234 ◽  
Author(s):  
Nidhi Rumpal ◽  
Gregory A. Lnenicka
Keyword(s):  
Plasma Membrane ◽  
Growth Cones ◽  
Explant Culture ◽  
Motor Axons ◽  
Rapid Decay ◽  
Mitochondrial Inhibitors ◽  
High K ◽  
Explant Cultures ◽  
Regulation Of Growth ◽  
Exchange Activity

Intracellular free Ca2+ concentration ([Ca2+]i) plays an important role in the regulation of growth cone (GC) motility; however, the mechanisms responsible for clearing Ca2+ from GCs have not been examined. We studied the Ca2+-clearance mechanisms in GCs produced by crayfish tonic and phasic motor axons by measuring the decay of [Ca2+]i after a high [K+] depolarizing pulse using fura-2AM. Tonic motor axons regenerating in explant cultures develop GCs with more rapid Ca2+ clearance than GCs from phasic axons. When Na/Ca exchange was blocked by replacing external Na+ with N-methyl-d-glucamine (NMG), [Ca2+]i decay was delayed in both tonic and phasic GCs. Tonic GCs appear to have higher Na/Ca exchange activity than phasic ones since reversal of Na/Ca exchange by lowering external Na+ caused a greater increase in [Ca2+]i for tonic than phasic GCs. Application of the mitochondrial inhibitors, Antimycin A1 (1 μM) and CCCP (10 μM), demonstrated that mitochondrial Ca2+ uptake/release was more prominent in phasic than tonic GCs. When both Na/Ca exchange and mitochondria were inhibited, the plasma membrane Ca2+ ATPase was effective in extruding Ca2+ from tonic, but not phasic GCs. We conclude that Na/Ca exchange plays a prominent role in extruding large Ca2+ loads from both tonic and phasic GCs. High Na/Ca exchange activity in tonic GCs contributes to the rapid decay of [Ca2+]i in these GCs; low rates of Ca2+ extrusion plus the release of Ca2+ from mitochondria prolongs the decay of [Ca2+]i in the phasic GCs.

GM1 ganglioside: another nuclear lipid that modulates nuclear calcium. GM1 potentiates the nuclear sodium–calcium exchangerThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 393-402 ◽  
Author(s):  
Robert W. Ledeen ◽  
Gusheng Wu
Keyword(s):  
Plasma Membrane ◽  
Neuroblastoma Cells ◽  
Genetically Engineered ◽  
Neural Cells ◽  
Special Issue ◽  
Sodium Calcium ◽  
A Cell ◽  
Induced Apoptosis ◽  
Selection Of ◽  
Exchange Activity

The nuclear envelope (NE) enclosing the cell nucleus, although morphologically and chemically distinct from the plasma membrane, has certain features in common with the latter including the presence of GM1 as an important modulatory molecule. This ganglioside influences Ca2+ flux across both membranes, but by quite different mechanisms. GM1 in the NE contributes to regulation of nuclear Ca2+ through potentiation of a Na+/Ca2+ exchanger in the inner nuclear membrane, whereas in the cell membrane, it regulates cytosolic Ca2+ through modulation of a nonvoltage-gated Ca2+ channel. Studies with neuroblastoma cells suggest GM1 concentration becomes elevated in the NE with onset of axonogenesis. However, the nuclear GM1/exchanger complex is not limited to neuronal cells but also occurs in NE of astrocytes, C6 cells, and certain non-neural cells. Immunoprecipitation and immunoblot experiments have shown high affinity association of the nuclear Na+/Ca2+ exchanger with GM1, in contrast to Na+/Ca2+ exchangers of the plasma membrane, which bind GM1 less avidly or not at all. This is believed to be due to different isoforms of the exchanger and a difference in topology of GM1 relative to the large inner loop of the exchanger in the 2 membranes. Cultured neurons from mice genetically engineered to lack GM1 suffered Ca2+ dysregulation as seen in their high vulnerability to Ca2+-induced apoptosis. They were rescued by GM1 and more effectively by LIGA20, a membrane-permeant derivative of GM1. The mutant animals were highly susceptible to kainate-induced seizures, which are also a reflection of Ca2+ dysregulation. The seizures were effectively attenuated by LIGA20 in parallel with the ability of this agent to enter brain cells, insert into the NE, and potentiate Na+/Ca2+ exchange activity in the nucleus. The Na+/Ca2+ exchanger of the NE, in association with nuclear GM1, is thus seen contributing to independent regulation of Ca2+ by the nucleus in a manner that provides cytoprotection against Ca2+-induced apoptosis.

Characterization of Na+?Ca2+ exchange activity in plasma membrane vesicles from postmortem human brain

1990 ◽  
Vol 15 (9) ◽  
pp. 881-887 ◽  
Author(s):  
Gary Hoel ◽  
Mary L. Michaelis ◽  
William J. Freed ◽  
J. E. Kleinman
Keyword(s):  
Plasma Membrane ◽  
Human Brain ◽  
Membrane Vesicles ◽  
Plasma Membrane Vesicles ◽  
Postmortem Human Brain ◽  
Exchange Activity

scholarly journals The protein kinase complex CBL10–CIPK8–SOS1 functions in Arabidopsis to regulate salt tolerance

2019 ◽  
Vol 71 (6) ◽  
pp. 1801-1814 ◽  
Author(s):  
Xiaochang Yin ◽  
Youquan Xia ◽  
Qing Xie ◽  
Yuxin Cao ◽  
Zhenyu Wang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Salt Tolerance ◽  
Wild Type ◽  
Arabidopsis Root ◽  
Transgenic Yeast ◽  
Na Efflux ◽  
Growth Phenotype ◽  
Better Than ◽  
Exchange Activity

Abstract Salt tolerance in plants is mediated by Na+ extrusion from the cytosol by the plasma membrane Na+/H+ antiporter SOS1. This is activated in Arabidopsis root by the protein kinase complex SOS2–SOS3 and in Arabidopsis shoot by the protein kinase complex CBL10–SOS2, with SOS2 as a key node in the two pathways. The sos1 mutant is more sensitive than the sos2 mutant, suggesting that other partners may positively regulate SOS1 activity. Arabidopsis has 26 CIPK family proteins of which CIPK8 is the closest homolog to SOS2. It is hypothesized that CIPK8 can activate Na+ extrusion by SOS1 similarly to SOS2. The plasma membrane Na+/H+ exchange activity of transgenic yeast co-expressing CBL10, CIPK8, and SOS1 was higher than that of untransformed and SOS1 transgenic yeast, resulting in a lower Na+ accumulation and a better growth phenotype under salinity. However, CIPK8 could not interact with SOS3, and the co-expression of SOS3, CIPK8, and SOS1 in yeast did not confer a significant salt tolerance phenotype relative to SOS1 transgenic yeast. Interestingly, cipk8 displayed a slower Na+ efflux, a higher Na+ level, and a more sensitive phenotype than wild-type Arabidopsis, but grew better than sos2 under salinity stress. As expected, sos2cipk8 exhibited a more severe salt damage phenotype relative to cipk8 or sos2. Overexpression of CIPK8 in both cipk8 and sos2cipk8 attenuated the salt sensitivity phenotype. These results suggest that CIPK8-mediated activation of SOS1 is CBL10-dependent and SOS3-independent, indicating that CIPK8 and SOS2 activity in shoots is sufficient for regulating Arabidopsis salt tolerance.

scholarly journals Ypt32 recruits the Sec4p guanine nucleotide exchange factor, Sec2p, to secretory vesicles; evidence for a Rab cascade in yeast

2002 ◽  
Vol 157 (6) ◽  
pp. 1005-1016 ◽  
Author(s):  
Darinel Ortiz ◽  
Martina Medkova ◽  
Christiane Walch-Solimena ◽  
Peter Novick
Keyword(s):  
Plasma Membrane ◽  
Guanine Nucleotide Exchange Factor ◽  
Secretory Vesicles ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Polarized Transport ◽  
Exchange Activity

SEC2 is an essential gene required for polarized growth of the yeast Saccharomyces cerevisiae. It encodes a protein of 759 amino acids that functions as a guanine nucleotide exchange factor for the small GTPase Sec4p, a regulator of Golgi to plasma membrane transport. Activation of Sec4p by Sec2p is needed for polarized transport of vesicles to exocytic sites. Temperature-sensitive (ts) mutations in sec2 and sec4 result in a tight block in secretion and the accumulation of secretory vesicles randomly distributed in the cell. The proper localization of Sec2p to secretory vesicles is essential for its function and is largely independent of Sec4p. Although the ts mutation sec2-78 does not affect nucleotide exchange activity, the protein is mislocalized. Here we present evidence that Ypt31/32p, members of Rab family of GTPases, regulate Sec2p function. First, YPT31/YPT32 suppress the sec2-78 mutation. Second, overexpression of Ypt31/32p restores localization of Sec2-78p. Third, Ypt32p and Sec2p interact biochemically, but Sec2p has no exchange activity on Ypt32p. We propose that Ypt32p and Sec4p act as part of a signaling cascade in which Ypt32p recruits Sec2p to secretory vesicles; once on the vesicle, Sec2p activates Sec4p, enabling the polarized transport of vesicles to the plasma membrane.

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