Biochemistry of the renal V-ATPase.

1992 ◽  
Vol 172 (1) ◽  
pp. 219-229 ◽  
Author(s):  
S L Gluck ◽  
R D Nelson ◽  
B S Lee ◽  
Z Q Wang ◽  
X L Guo ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Function ◽  
Proton Pumps ◽  
Intracellular Membrane ◽  
Acid Base Balance ◽  
Intracellular Compartments ◽  
Selective Membrane ◽  
Base Balance ◽  
Membrane Compartments ◽  
High Concentrations

In most eukaryotic cells, vacuolar H(+)-ATPases (V-ATPases) are present primarily or exclusively in intracellular membrane compartments, functioning in the acidification of the endocytic and secretory vacuolar apparatus necessary for constitutive cell function. V-ATPases also participate in renal hydrogen ion secretion in both the proximal and distal nephron, residing at high concentrations on the plasma membrane, where they are regulated physiologically to maintain the acid-base balance of the organism. Recent experiments have begun to reveal how the kidney controls transcellular proton transport while still maintaining acidification of intracellular compartments. Control may occur by recruitment of proton pumps to or away from the plasma membrane. The proton-transporting plasma membrane of intercalated cells is a specialized apparatus that translocates the enzyme between an intracellular membrane pool and the plasma membrane in response to physiological stimuli. Regulation may also occur by changes in the kinetics of the V-ATPase. V-ATPases are a family of structurally similar enzymes which differ in the composition of specific subunits. Cytosolic regulatory enzymes present in renal cells may preferentially affect V-ATPases in selective membrane compartments.

Influence of bafilomycin A1on pHi responses in cultured rabbit nonpigmented ciliary epithelium

1997 ◽  
Vol 273 (5) ◽  
pp. C1700-C1706 ◽  
Author(s):  
Qiang Wu ◽  
Nicholas A. Delamere
Keyword(s):  
Plasma Membrane ◽  
Disulfonic Acid ◽  
Ciliary Epithelium ◽  
Free Medium ◽  
Acid Base Balance ◽  
Carbonyl Cyanide ◽  
Base Balance ◽  
Rich Solution ◽  
Cytoplasmic Acidification ◽  
Nonpigmented Ciliary Epithelium

Aqueous humor secretion is in part linked to [Formula: see text]transport by nonpigmented ciliary epithelium (NPE) cells. During this process, the cells must maintain stable cytoplasmic pH (pHi). Because a recent report suggests that NPE cells have a plasma membrane-localized vacuolar H+-ATPase, the present study was conducted to examine whether vacuolar H+-ATPase contributes to pHi regulation in a rabbit NPE cell line. Western blot confirmed vacuolar H+-ATPase expression as judged by H+-ATPase 31-kDa immunoreactive polypeptide in both cultured NPE and native ciliary epithelium. pHi was measured using 2′,7′-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). Exposing cultured NPE to K+-rich solution caused a pHi increase we interpret as depolarization-induced alkalinization. Alkalinization was also caused by ouabain or BaCl2. Bafilomycin A1 (0.1 μM; an inhibitor of vacuolar H+-ATPase) inhibited the pHi increase caused by high K+. The pHi increase was also inhibited by angiotensin II and the metabolic uncoupler carbonyl cyanide m-chlorophenylhydazone but not by ZnCl2, 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid (SITS), 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS), omeprazole, low-Cl−medium, [Formula: see text]-free medium, or Na+-free medium. Bafilomycin A1 slowed the pHi increase after an NH4Cl (10 mM) prepulse. However, no detectable pHi change was observed in cells exposed to bafilomycin A1 under control conditions. These studies suggest that vacuolar H+-ATPase is activated by cytoplasmic acidification and by reduction of the proton electrochemical gradient across the plasma membrane. We speculate that the mechanism might contribute to maintenance of acid-base balance in NPE.

Membrane recycling and epithelial cell function

1989 ◽  
Vol 256 (1) ◽  
pp. F1-F12 ◽  
Author(s):  
D. Brown
Keyword(s):  
Plasma Membrane ◽  
Cell Function ◽  
Collecting Duct ◽  
Water Channel ◽  
Cell Types ◽  
Apical Plasma Membrane ◽  
Proton Pumps ◽  
Intercalated Cells ◽  
Membrane Recycling ◽  
Membrane Composition

The plasma membrane composition of virtually all eucaryotic cells is established, maintained, and modified by the process of membrane recycling. Specific plasma membrane components are inserted by exocytosis of transport vesicles, and are removed by endocytosis of segments of the membrane in which particular proteins are concentrated. In the kidney collecting duct, vasopressin induces the cycling of vesicles that are thought to carry water channels to and from the apical plasma membrane of principal cells, thus modulating the water permeability of this membrane. In the intercalated cells of the collecting duct, hydrogen ion secretion is controlled by the recycling of vesicles carrying proton pumps to and from the plasma membrane. In both cell types, "coated" carrier vesicles are involved, but whereas clathrin-coated vesicles participate in water channel recycling, the vesicles in intercalated cells are coated with the cytoplasmic domains of proton pumps. Following a brief outline of membrane recycling in general, this review summarizes previous data on membrane recycling in the collecting duct and related transporting epithelia and discusses some selected points relating to the role of membrane recycling and cell-specific function in the collecting duct.

scholarly journals The Chemical Composition and the Acid Base Balance of Archidoris Britannica

1937 ◽  
Vol 22 (1) ◽  
pp. 273-280 ◽  
Author(s):  
R. A. McCance ◽  
M. Masters
Keyword(s):  
Sea Water ◽  
Potassium Phosphate ◽  
The Body ◽  
Mineral Matter ◽  
Acid Base Balance ◽  
Visceral Mass ◽  
Base Balance ◽  
Inorganic Composition ◽  
Calcium And Magnesium ◽  
High Concentrations

The body of Archidoris britannica contains very high concentrations of calcium and magnesium which appear to be combined mostly with CO3 and fluoride. The bulk of these materials are in solid deposits throughout the submucous tissue. Sodium chloride and potassium phosphate account for most of the residual mineral matter.The mucus secreted by the body has an inorganic composition resembling sea water.The visceral mass contains only one-tenth as much calcium and magnesium as the body. The predominating bases are potassium and sodium and the acid radicles are essentially chlorides and phosphates.

Initial entry of IRAP into the insulin-responsive storage compartment occurs prior to basal or insulin-stimulated plasma membrane recycling

2005 ◽  
Vol 289 (5) ◽  
pp. E746-E752 ◽  
Author(s):  
Gang Liu ◽  
June Chunqiu Hou ◽  
Robert T. Watson ◽  
Jeffrey E. Pessin
Keyword(s):  
Plasma Membrane ◽  
Enhanced Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Brefeldin A ◽  
Intracellular Membrane ◽  
Receptor Endocytosis ◽  
Membrane Compartments ◽  
Insulin Responsiveness ◽  
Green Fluorescent ◽  
Syntaxin 3

To examine the acquisition of insulin sensitivity after the initial biosynthesis of the insulin-responsive aminopeptidase (IRAP), 3T3-L1 adipocytes were transfected with an enhanced green fluorescent protein-IRAP (EGFP-IRAP) fusion protein. In the absence of insulin, IRAP was rapidly localized (1–3 h) to secretory membranes and retained in these intracellular membrane compartments with little accumulation at the plasma membrane. However, insulin was unable to induce translocation to the plasma membrane until 6–9 h after biosynthesis. This was in marked contrast to another type II membrane protein (syntaxin 3) that rapidly defaulted to the plasma membrane 3 h after expression. In parallel with the time-dependent acquisition of insulin responsiveness, the newly synthesized IRAP protein converted from a brefeldin A-sensitive to a brefeldin A-insensitive state. The initial trafficking of IRAP to the insulin-responsive compartment was independent of plasma membrane endocytosis, as expression of a dominant-interfering dynamin mutant (Dyn/K44A) inhibited transferrin receptor endocytosis but had no effect on the insulin-stimulated translocation of the newly synthesized IRAP protein.

Temperature and acid—base balance in ectothermic vertebrates: the imidazole alphastat hypotheses and beyond

2002 ◽  
Vol 205 (23) ◽  
pp. 3587-3600 ◽  
Author(s):  
Richard F. Burton
Keyword(s):  
Cell Function ◽  
The Body ◽  
Published Data ◽  
Passive Component ◽  
Ph Homeostasis ◽  
Acid Base Balance ◽  
Other Information ◽  
Base Balance ◽  
Fish Cells ◽  
Temperature Responses

SUMMARY The `imidazole alphastat hypothesis' states that intracellular and extracellular pH, partly via buffering by imidazole groups, change with temperature in a way that keeps imidazole and protein ionization constant, thus maintaining cell function and minimizing shifts of base equivalents and total CO2, while adjustment of PCO2 involves imidazole-based receptors. `The hypothesis', which is actually several hypotheses, has been variously perceived and judged, but its underlying conceptual framework remains largely valid, and is reformulated using differential equations requiring less information input than their integral equivalents. Their usefulness is illustrated with published data on temperature responses in fish cells and whole tetrapods. Mathematical modelling allows general principles to be explored with less immediate concern for uncertainties in experimental data and other information. In tetrapods, it suggests that warming is followed by a loss of base equivalents from the body, and that this loss is due to metabolic adjustments that are not part of pH homeostasis. Uncertainties include intracellular buffer values, local variations in PCO2 within the body, the possible role of buffering by bone mineral, and the temperature dependence of pK values for CO2/HCO3- and imidazole groups. The equations utilize a single, notional, temperature-dependent pK value for all non-bicarbonate buffers in a given body compartment. This approximates to the`passive component' of pH adjustment to temperature change as measured by the homogenate technique. Also discussed are the diversity of cell responses within individual animals, relevant aspects of the control of ventilation,metabolism and transmembrane transport, and the basis of optimum pH—temperature relationships.

scholarly journals Asynchronous assembly of the acetylcholine receptor and of the 43-kD nu1 protein in the postsynaptic membrane of developing Torpedo marmorata electrocyte.

1989 ◽  
Vol 108 (1) ◽  
pp. 127-139 ◽  
Author(s):  
E Kordeli ◽  
J Cartaud ◽  
H O Nghiêm ◽  
A Devillers-Thiéry ◽  
J P Changeux
Keyword(s):  
Plasma Membrane ◽  
Acetylcholine Receptor ◽  
Postsynaptic Membrane ◽  
Synaptic Membrane ◽  
Asymmetric Distribution ◽  
Subsequent Stage ◽  
Torpedo Marmorata ◽  
Intracellular Compartments ◽  
Membrane Compartments

The assembly of the nicotinic acetylcholine receptor (AchR) and the 43-kD protein (v1), the two major components of the post synaptic membrane of the electromotor synapse, was followed in Torpedo marmorata electrocyte during embryonic development by immunocytochemical methods. At the first developmental stage investigated (45-mm embryos), accumulation of AchR at the ventral pole of the newly formed electrocyte was observed within columns before innervation could be detected. No concomitant accumulation of 43-kD immunoreactivity in AchR-rich membrane domains was observed at this stage, but a transient asymmetric distribution of the extracellular protein, laminin, which paralleled that of the AchR, was noticed. At the subsequent stage studied (80-mm embryos), codistribution of the two proteins was noticed on the ventral face of the cell. Intracellular pools of AchR and 43-kD protein were followed at the EM level in 80-mm electrocytes. AchR immunoreactivity was detected within membrane compartments, which include the perinuclear cisternae of the endoplasmic reticulum and the plasma membrane. On the other hand, 43-kD immunoreactivity was not found associated with the AchR in the intracellular compartments of the cell, but codistributed with the AchR at the level of the plasma membrane. The data reported in this study suggest that AchR clustering in vivo is not initially determined by the association of the AchR with the 43-kD protein, but rather relies on AchR interaction with extracellular components, for instance from the basement membrane, laid down in the tissue before the entry of the electromotor nerve endings.

Acid-Base Balance and Removal of Injected Calcium From the Circulation

1957 ◽  
Vol 191 (2) ◽  
pp. 377-383 ◽  
Author(s):  
Smith Freeman ◽  
Anne B. Jacobsen ◽  
Billy James Williamson
Keyword(s):  
Carbon Dioxide ◽  
Respiratory Acidosis ◽  
High Plasma ◽  
Acid Base Balance ◽  
Acid Base ◽  
Essentially Normal ◽  
Base Balance ◽  
Normal Carbon ◽  
Rapid Removal ◽  
High Concentrations

A study was made of the effect of acute disturbances in acid-base balance in otherwise healthy adult dogs, on the rate of removal from the circulation of injected calcium (15 mg/kg). A marked increase in the rate of removal of injected calcium was observed to occur in all animals having high plasma bicarbonate values, except those with respiratory acidosis. The most rapid removal of injected calcium, approximately five times the normal rate, occurred in animals with alkali excess compensated by the inhalation of high concentrations of carbon dioxide. The accelerated removal of injected calcium could not be accounted for by increased excretion in the urine. These animals had essentially normal blood ph values. The calcium space was reduced in ammonium chloride acidosis, but the slope of the disappearance curve for calcium was normal. Carbon dioxide excess was accompanied by an elevation of the plasma concentration of inorganic phosphate.

Regulated expression of pendrin in rat kidney in response to chronic NH4Cl or NaHCO3 loading

2003 ◽  
Vol 284 (3) ◽  
pp. F584-F593 ◽  
Author(s):  
Sebastian Frische ◽  
Tae-Hwan Kwon ◽  
Jørgen Frøkiær ◽  
Kirsten M. Madsen ◽  
Søren Nielsen
Keyword(s):  
Plasma Membrane ◽  
Sodium Intake ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Apical Plasma Membrane ◽  
Cortical Collecting Duct ◽  
Acid Base Balance ◽  
Acid Base ◽  
Control Value ◽  
Base Balance

The anion exchanger pendrin is present in the apical plasma membrane of type B and non-A-non-B intercalated cells of the cortical collecting duct (CCD) and connecting tubule and is involved in HCO[Formula: see text]secretion. In this study, we investigated whether the abundance and subcellular localization of pendrin are regulated in response to experimental metabolic acidosis and alkalosis with maintained water and sodium intake. NH4Cl loading (0.033 mmol NH4Cl/g body wt for 7 days) dramatically reduced pendrin abundance to 22 ± 4% of control values ( n = 6, P < 0.005). Immunoperoxidase labeling for pendrin showed reduced intensity in NH4Cl-loaded animals compared with control animals. Moreover, double-label laser confocal microscopy revealed a reduction in the fraction of cells in the CCD exhibiting pendrin labeling to 65% of the control value ( n = 6, P < 0.005). Conversely, NaHCO3 loading (0.033 mmol NaHCO3/g body wt for 7 days) induced a significant increase in pendrin expression to 153 ± 11% of control values ( n = 6, P < 0.01) with no change in the fraction of cells expressing pendrin. Immunoelectron microscopy revealed no major changes in the subcellular distribution, with abundant labeling in both the apical plasma membrane and the intracellular vesicles in all conditions. These results indicate that changes in pendrin protein expression play a key role in the well-established regulation of HCO[Formula: see text] secretion in the CCD in response to chronic changes in acid-base balance and suggest that regulation of pendrin expression may be clinically important in the correction of acid-base disturbances.

scholarly journals Probing the subcellular distribution of phosphatidylinositol reveals a surprising lack at the plasma membrane

2020 ◽  
Vol 219 (3) ◽  
Author(s):  
James P. Zewe ◽  
April M. Miller ◽  
Sahana Sangappa ◽  
Rachel C. Wills ◽  
Brady D. Goulden ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Subcellular Localization ◽  
Subcellular Distribution ◽  
Eukaryotic Cells ◽  
Intracellular Membrane ◽  
Membrane Function ◽  
Membrane Compartments ◽  
Health And Disease ◽  
Structural Lipid ◽  
And Function

The polyphosphoinositides (PPIn) are central regulatory lipids that direct membrane function in eukaryotic cells. Understanding how their synthesis is regulated is crucial to revealing these lipids’ role in health and disease. PPIn are derived from the major structural lipid, phosphatidylinositol (PI). However, although the distribution of most PPIn has been characterized, the subcellular localization of PI available for PPIn synthesis is not known. Here, we used several orthogonal approaches to map the subcellular distribution of PI, including localizing exogenous fluorescent PI, as well as detecting lipid conversion products of endogenous PI after acute chemogenetic activation of PI-specific phospholipase and 4-kinase. We report that PI is broadly distributed throughout intracellular membrane compartments. However, there is a surprising lack of PI in the plasma membrane compared with the PPIn. These experiments implicate regulation of PI supply to the plasma membrane, as opposed to regulation of PPIn-kinases, as crucial to the control of PPIn synthesis and function at the PM.

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