The Lysosomal Proton Pump

Harikumar, P.; Reeves, John P.

doi:10.1007/978-1-4684-5062-0_4

Cited by 11 publications

(13 citation statements)

References 27 publications

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“…Such a localization for the tubular HCO3-ATPase is most unlikely since the lysosomal proton pump is also sensitive to NEM [20], and furthermore, the distribution along the nephron of lysosomal markers such as acid phosphatase and N-acetyl-D-glucosaminidase [30,39] is quite different from the profile of HCO~-ATPase.…”

Section: Effects Of Doca Treatmentmentioning

confidence: 96%

Presence of an extramitochondrial anion-stimulated ATPase in the rabbit kidney: Localization along the nephron and effect of corticosteroids

1986

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To determine whether kidney membrane fractions contain an extramitochondrial anion-stimulated ATPase, we compared the pharmacological and kinetic properties of HCO3-ATPase activities in mitochondrial and microsomal fractions prepared from rabbit kidney cortex and outer medulla. The results indicated that this activity differed markedly in each type of fraction. Microsomal HCO3-ATPase was less sensitive than mitochondrial ATPase to azide, oligomycin, DCCD and thiocyanate, but was more sensitive to filipin and displayed different dependency towards ATP, magnesium and pH. Microsomal ATPase activity was stimulated by sulfite much more strongly than by bicarbonate, whereas mitochondrial activity was stimulated by both these anions to a similar extent. These results demonstrate the presence of an extramitochondrial HCO3-ATPase in kidney membrane fractions. HCO3-ATPase was also measured in single microdissected segments of the rabbit nephron using a radiochemical microassay previously developed for tubular Na, K-ATPase activity. An enzyme with the pharmacological and kinetic properties of the microsomal enzyme was detected in both proximal tubule, distal convoluted tubule and collecting duct, but the thick ascending limb was devoid of any detectable activity. Long-term DOCA administration markedly increased HCO3-ATPase activity in the distal convoluted and collecting tubule. The insensitivity of microsomal HCO3-ATPase to vanadate indicates that it belongs to the F0-F1 class of ATPases, and might therefore be involved in proton transport. This hypothesis is also supported by the localization of tubular HCO3-ATPase activity at the sites of urinary acidification.

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Section: Effects Of Doca Treatmentmentioning

confidence: 96%

Presence of an extramitochondrial anion-stimulated ATPase in the rabbit kidney: Localization along the nephron and effect of corticosteroids

1986

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“…Another common feature of this class of H+-ATPases is the stimulatory effect of anions on H + pump activity. For microsomal vesicles from rat pancreatic acinar cells (Th6venod et al, 1989) as well as for vesicles from Golgi apparatus from rat liver (Glickman et al, 1983), lysosomes from rat kidney cortex (Harikumar & Reeves, 1983), clathrin-coated vesicles from bovine brain , endoplasmic reticulum vesicles from rat parotid gland (Th6venod & Schulz, 1988) and endocytotic vesicles from rat, pig and rabbit kidney cortex (Sabolic & Burckhardt, 1986;Burckhardt, Moewes & Sabolic, 1987;Hilden, Johns & Madias, 1988) an anion conductance in parallel to the ATP-dependent H + translocation system could be demonstrated. Inhibition of the anion permeability in clathrin-coated vesicles and kidney endosomes by blocker substances led to a decrease of ATP-dependent H + uptake into the vesicles, indicating a functional correlation of H + pump and anion permeability.…”

Section: Introductionmentioning

confidence: 99%

Single chloride channels in endosomal vesicle preparations from rat kidney cortex

1989

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Endocytotic vesicles from rat kidney cortex, isolated by differential centrifugation and enriched on a Percoll gradient, contain both an electrogenic H+ translocation system and a conductive chloride pathway. Using the dehydration/rehydration method, we fused vesicles of enriched endosomal vesicle preparations and thereby made them accessible to the patch-clamp technique. In the fused vesicles, we observed Cl- channels with a single-channel conductance of 73 +/- 2 pS in symmetrical 140 mM KCl solution (n = 25). The current-voltage relationship was linear in the range of -60 to +80 mV, but channel kinetic properties depended on the clamp potential. At positive potentials, two sublevels of conductance were discernible and the mean open time of the channel was 10-15 msec. At negative voltages, only one substate could be resolved and the mean open time decreased to 2-6 msec. Clamp voltages more negative than -50 mV caused reversible channel inactivation. The channel was selective for anions over cations. Ion substitution experiments revealed an anion permeability sequence of Cl- = Br- = I- greater than SO4(2-) approximately F-. Gluconate, methanesulfonate and cyclamate were impermeable. The anion channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, 1.0 mM) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB, 0.1 mM) totally inhibited channel activity. Comparisons with data obtained from radiolabeled Cl(-)-flux measurements and studies on the H+ pump activity in endocytotic vesicle suspensions suggest that the channel described here is involved in maintenance of electroneutrality during ATP-driven H+ uptake into the endosomes.

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“…We believe this treatment is important for the following reason: The pH gradient across lysosomal membranes produces an inside negative membrane potential. An increase in the lysosomal H + permeability causes the internal membrane potential to become more negative (Harikumar and Reeves, 1983). As shown in the following experiments, the PLA 2 treatment could increase the lysosomal H + permeability (cf.…”

Section: Effects Of Pla 2 On the Lysosomal K + Permeabilitymentioning

confidence: 95%

“…Normal lysosomes show only a limited permeability toward K + , which is favorable for the maintenance of lysosomal osmotic stability (Harikumar and Reeves, 1983). The effect of PLA 2 on the lysosomal K + permeability was examined using the widely used osmotic protection assay (Casey et al, 1978;Ruth and Weglicki, 1982).…”

Section: Effects Of Pla 2 On the Lysosomal K + Permeabilitymentioning

confidence: 99%

Effects of phospholipase A2 on the lysosomal ion permeability and osmotic sensitivity

Wang¹,

Sun²,

Hu³

et al. 2006

Chemistry and Physics of Lipids

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The Lysosomal Proton Pump

Cited by 11 publications

References 27 publications

Presence of an extramitochondrial anion-stimulated ATPase in the rabbit kidney: Localization along the nephron and effect of corticosteroids

Presence of an extramitochondrial anion-stimulated ATPase in the rabbit kidney: Localization along the nephron and effect of corticosteroids

Single chloride channels in endosomal vesicle preparations from rat kidney cortex

Effects of phospholipase A2 on the lysosomal ion permeability and osmotic sensitivity

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