ATPase calcium transport

C. Phosphate ion depletes cellular levels of ATP resulting in inhibition of Ca +-ATPase calcium transporters. 

Darter s disease Darier s disease is an autosomal dominant skin disease with a mutation in the ATP2A2 gene (ATPase, calcium-transporting, cardiac muscle, slow twitch 2). Nearly half of all patients with Darier s disease have a mood disorder 30% have major depression and 4% have bipolar illness [55 ]. A woman with Darier s disease reported that her skin condition flared up when she took lithium [56" ]. 

Inhibition of Ca2+ ATPases. Compounds, which react with sulfydryl groups, will inhibit the ATPases, which are involved in calcium transport. Thus, intracellular... 

Table 3. Molecular weight of the solubilized calcium transport ATPase...

It was very early recognized that the calcium transport and the calcium-dependent ATPase could simultaneously be blocked by thiol reagents26). In contrast to various other thiol containing enzymes the activities of the sarcoplasmic reticulum membranes cannot be restored when the blocking agents are removed. 

Degradation and Restitution of the Calcium-Dependent ATPase and Calcium Transport... 

While reconstitution of the calcium-dependent ATPase from the lipid deprived enzyme can easily be achieved, attempts to reconstitute simultaneously the abolished accumulation of calcium had no success55,70. Yet, in a number of reports the reconstitution of calcium transport from the enzyme after purification and/or after lipid exchange has been described160,, 70 172) jn these experiments it was attempted to reconstitute vesicles which could retain calcium ions which were transported into the vesicular space by the transport protein across the lipid bilayer. Different lipid pro-... 

Long-range intramolecular linked functions in the calcium transport ATPase. Adv. Enzymol. 65 182, 1992. 

A variety of other calcium transport systems are associated with Ca21-activated ATPases. The extraembryonic structure, the chorioallantoic membrane, of the chick embryo is responsible for the translocation of over 120 mg of eggshell calcium into (he embryo during development. The enzyme responsible for this is a (Ca2+, Mg2+)-ATPase with Km values for Ca2+ of 30 p,mol dm-3 and 0.3 mmol dm-3, and a molecular weight of 170 000. The enzyme can be crossiinked and co-isolated with a calcium-binding protein.158 Transport of Ca2+ is also associated with (Ca2+, Mg2+)-ATPases in neutrophil plasma membranes,159 transverse tubule membranes from rabbit skeletal muscle,160 rabbit myocardial membrane,161 endoplasmic reticulum,162 sar-colemma,163 brain microsomes,164 the Golgi apparatus165 and rat liver plasma membranes.166... 

Reinhardt, T.A., Lippolis, J.D., Shull, G.E., Horst, R.L., 2004, Null mutation in the gene encoding plasma membrane Ca2+-ATPase isoform 2 impairs calcium transport into milk. J Biol Chem 279, 42369 12373. 

Brouland, J. P., Gelebart, P., Kovacs, T., Enouf, J., Grossmann, J. and Papp, B., 2005, The loss of sarco/endoplasmic reticulum calcium transport ATPase 3 expression is an early event during the multistep process of colon carcinogenesis. Am J Pathol 167, 233-42. 

Mas-Oliva, J., Perez-Montfort, R., Cardenas-Garcia, M. and Rivas-Duro, M., 1991, Altered coupling states between calcium transport and (Ca2+, Mg2+)-ATPase in the AS-30D ascites hepatocarcinoma plasma membrane. Mol Cell Biochem 100, 39—50. 

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)...

Schematic diagram of a cardiac muscle sarcomere, with sites of action of several drugs that alter contractility (numbered structures). Site 1 is Na+/K+ ATPase, the sodium pump. Site 2 is the sodium/calcium exchanger. Site 3 is the voltage-gated calcium channel. Site 4 is a calcium transporter that pumps calcium into the sarcoplasmic reticulum (SR). Site 5 is a calcium channel in the membrane of the SR that is triggered to release stored calcium by activator calcium. Site 6 is the actin-troponin-tropomyosin complex at which activator calcium brings about the contractile interaction of actin and myosin.

Blasie, J.K., Pascolini, D., Asturias, F., Herbette, L.G., Pierce, D., Scarpa, A. (1990). Large-scale structural changes in the sarcoplasmic reticulum ATPase appear essential for calcium transport. Biophys. J. 58, 687-693. 

Levy, D., Seigneuret, M., Bluzat, A., Rigaud, J.-L. (1990). Evidence for proton countertransport by the sarcoplasmic reticulum Ca2+-ATPase during calcium transport in reconstituted proteo-liposomes with low ionic permeability. J. Biol. Chem. 265,19524-19534. 

Figure 11.4. Schematics of calcium transport with Ca2+-ATPase liposome, ionophore (A), and leaks, lonophore A23187 induces uptake of Ca2+ions. Leaks are shown with dashed arrows, i is interior (alkaline) and e is exterior (acidic). Scalar flow of ATP hydrolysis...

These ion movements are shown schematically in Figure 11. It should be noted that the orientation of the protonmotive force is reversed from that in vivo. The proton-pumping Mg -ATPase will be described in a later section. This calcium transport system is not inhibited significantly by ruthenium red, the classical inhibitor for calcium uptake in mitochondria. However, uptake of Ca by these inside-out vesicles of E. coli is inhibited dramatically by a dimeric, mixed-valence complex of Ru" ", [(NH3)3RuCl3Ru(NH3)3]. The mode of action remains to be established. 

Ca -ATPase (calcium pump) A protein found in the plasma membrane that uses a mechanism of active transport to move calcium ions across the membrane. 

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