ATPase vacuolar

Synaptic vesicles isolated from brain exhibit four distinct vesicular neurotransmitter transport activities one for monoamines, a second for acetylcholine, a third for the inhibitory neurotransmitters GABA and glycine, and a fourth for glutamate [1], Unlike Na+-dependent plasma membrane transporters, the vesicular activities couple to a proton electrochemical gradient (A. lh+) across the vesicle membrane generated by the vacuolar H+-ATPase ( vacuolar type proton translocating ATPase). Although all of the vesicular transport systems rely on ApH+, the relative dependence on the chemical and electrical components varies (Fig. 1). The... 

Figure 5. Components and processes of a membrane-bound organelle, representing either a Protein Storage Vacuole (PSV) or a membrane-bound globoid found within a compound PSV V-PPase = vacuolar inorganic pyrophosphatase. V-ATPase = vacuolar ATPase. TIP = Tonoplast Intrinsic Protein. Ptdlns = phosphatidylinositol. DAG = diacylglycerol. Questionmarks indicate purely speculative aspects of the diagram.

Vacuolar-type proton translocating ATPase is a heter-eomeric protein complex, which appears to translocate two protons across the vesicle membrane for each ATP molecule that is hydrolyzed, generating chemical (ApH) and electrical (A ) gradients. Although the ATPases present on different classes of intracellular vesicle have... 

In addition to direct inhibition of the vesicular transport protein, storage of neurotransmitters can be reduced by dissipation of the proton electrochemical gradient. Bafilomycin (a specific inhibitor of the vacuolar H+-ATPase), as well as the proton ionophores carbonyl cyanide m-chlorophenylhydrazone (CCCP) and carbonylcyanide p-(trifluoromethoxy) phenylhy-drazone (FCCP) are used experimentally to reduce the vesicular storage of neurotransmitters. Weak bases including amphetamines and ammonium chloride are used to selectively reduce ApH. 

Struve, I., Weber, A., Liittge, U., Ball, E. Smith, J.A.C. (1985). Increased vacuolar ATPase activity correlated with CAM induction in Mesembryanthemum crystallinum and Kalanchoe blossfeldiana cv. Tom Thumb. Journal of Plant Physiology, 117, 451-68. 

CJ Swallow, S Grinstein, OD Rotstein. (1990). A vacuolar type H+-ATPase regulates cytoplasmic pH in murine macrophages. J Biol Chem 265 7645-7654. 

Arata, Y., Nish, T., Kawasaki-Nishi, S., Shao, E., Wilkens, S. and Forgac, M. Structure, subunit function and regulation of the coated vesicle and yeast vacuolar H - ATPases. Biochim. Biophys. Acta 1555 71-74, 2002. 

Morel, N. Neurotransmitter release the dark side of the vacuolar-H+ATPase. Biol Cell. 95 453-457, 2003. 

Azuma, M., and Ohta, Y. (1998). Changes in H+ -translocating vacuolar-type ATPase in the anterior silk gland cell of Bombyx mod during metamorphosis./. Exp. Biol. 201, 479-486. 

The macrolide antibiotic bafilomycin Al and concanamycin A are specific inhibitors of vacuolar-type H(- -)-ATPase, which prevents the acidification of endosomes and lysosomes and increases the intralysosomal pH from about 5.1-5.5 to about 6.3 (61,84-87). Bafilomycin Al is applied in concentrations ranging from 25-1000 nM and is incubated for 30 to 60 minutes in the presence or absence of serum. We observed maximal effects in COS-7 and HUVEC with concentrations of 100-200 nM and an incubation time of 60 minutes. 

Clague Ml, Urbe S, Aniento F, Gruenberg J. Vacuolar ATPase activity is required for endosomal carrier vesicle formation. J Biol Chem 1994 269(1) 21-24. 

Yoshimori T, Yamamoto A, Moriyama Y, Futai M, Tashiro Y. Bafilomycin Al, a specific inhibitor of vacuolar-type H(+)-ATPase, inhibits acidification and protein degradation in lysosomes of cultured cells. J Biol Chem 1991 266(26) 17707-17712. 

Tcirgl (ATP6i) A3 subunit of the vacuolar proton ATPase oc allele in the monse Osteopetrosis with increased number of inactive osteoclasts, failure of tooth eruption Majority of cases of malignant infantile osteopetrosis Chondrodysplasia, small size, premature death... 

There are few studies on vacuolar importation of flavonoids other than anthocyanins and PAs. Klein et al. reported uptake of flavone glycosides by isolated H. vulgare primary leaf vacuoles via a vacuolar H -ATPase linked mechanism,and by vacuoles from Secale cereale (rye) mesophyll via a possible ABC transporter mechanism. Li et al. "" found medicarpin conjugated to glutathione was also sequestered by an ABC transporter mechanism. 

Adociasulfates 1-6 (380-385) were isolated from a Haliclona (aka Adocia) sp. from Palau and were all inhibitors of kinesin motor proteins [331]. Adociasulfate 2 (381) had earlier been shown to inhibit the activity of the motor protein kinesin by interference with its binding to microtubules [332], An Adocia sp. from the Great Barrier Reef contained adociasulfates 1 (380), 7 (386) and 8 (387), which inhibit vacuolar H -ATPase [333]. Adociasulfates 5 (384) and 9 (388) were obtained from Adocia aculeata from the Great Barrier Reef [334], The structure of adociasulfate 1 (380) was confirmed by an enantioselective total synthesis [335]. Adociasulfate 10 (389) from Haliclona sp. from Palau also inhibits the kinesin motor proteins [336]. 

Two other types of proton-pumping ATPases are considered in Chapter 18. One is the mitochondrial F,F0 ATPase, which ordinarily operates in the reverse direction as the body s principal ATP synthase. The other type, which in some ways resembles the mitochondrial FjFq ATPase, is the vacuolar ATPase (V-ATPase). These are true proton pumps which acidify vacuoles of plants and also lysosomes and phagocytic vacuoles.554 555 They are also considered in Chapter 18. 

One of the first inteins discovered was found in the 119-kDa precursor to a subunit of a vacuolar ATPase of yeast.a,c In this 50-kDa intein Thr 72, His 75, and His 197 may have catalytic functions.d The intein is spliced out to form the 69-kDa subunit. 

Figure 2. Bulk calcium transport by the osteoclast. Net acid transport is driven by the vacuolar-type H+-ATPase with a specialized large membrane subunit. Transport is balanced by chloride transport, probably involving both a chloride channel (CLIC-5) and a chloride bicarbonate antiporter (CLCN7). Supporting transport processes include chloride-bicarbonate exchange. Insertion of transporters is specific for subcellular locations and involves interaction of transporters with specific cytoskeletal components, including actin (See Colour Plate 29)...

Finbow ME, Harrison MA. 1997. The vacuolar H+-ATPase a universal proton pump of eukaryotes. Biochem J 324 697-712. 

Mattsson JP, Li X, Peng S-B, Nilsson F, Adersen P, Lundberg LG, Stone DK, Keeling DJ. 2000. Properties of three isoforms of the 116-kDa Subunit of vacuolar H+-ATPase from a single vertebrate species. Cloning, gene expression and protein characterization of functionally distinct isoforms in Gallus domesticus. Euro J Bioch 267 4115-26. 

Nishi T, Forgac M. 2002. The vacuolar H+-ATPases - Natures most versitile proton pumps. Nature Rev 3 94-102. 

Zuo J, Jiang J, Chen SH, Vergara S, Gong Y, Xue J, Huang H, Kaku M, Holliday LS. 2006, Actin binding activity of subunit B of vacuolar H+-ATPase is involved in its targeting to ruffled membranes of osteoclasts. J Bone Miner Res 21 714-21. 

The F-, V-, and A-ATPases constitute a family of ATP hydrolysis-driven ion pumps which are found in Archaea, eubacteria, simple eukaryotes such as yeast, and higher eukaryotes including plants and mammals. The family of ion pumps is divided into three subfamilies the F-ATPases (which function mainly as ATP synthases), the vacuolar ATPases (which function solely as ATP hydrolysis-driven ion pumps) and the Archaeal A-type ATPases (whose function can be either in the direction of ATP synthesis or hydrolysis). All three members of the family are evolutionarily related, and it is believed that the three subfamilies have arisen from a common ancestor. 

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