Ligand-gated channel of the sarcoplasmic reticulum Ca2+ transport ATPase

Wolosker, Herman; Meis, L de

doi:10.1007/bf01788368

Cited by 12 publications

(6 citation statements)

References 49 publications

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“…It has been shown in previous reports that Ca# + leaks through the skeletal muscle Ca# + -ATPase when vesicles previously loaded with Ca# + are incubated in media containing none of the ligands of the ATPase [55,56]. This efflux is not coupled to the synthesis of ATP and is referred to as passive Ca# + efflux.…”

Section: Ph-dependence Of Ca 2 + Effluxmentioning

confidence: 99%

“…This efflux is not coupled to the synthesis of ATP and is referred to as passive Ca# + efflux. The rate of passive Ca# + efflux is decreased when thapsigargin or one of the ligands of the pump, such as Ca# + , Mg# + or K + , is added to the efflux medium [55][56][57]. The effectiveness of cations in blocking the passive efflux of Ca# + from skeletal muscle vesicles is decreased at acidic pH [48].…”

Section: Ph-dependence Of Ca 2 + Effluxmentioning

confidence: 99%

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Sarco/endoplasmic reticulum Ca2+-ATPase isoforms: diverse responses to acidosis

Wolosker

Rocha

Engelender

et al. 1997

Biochemical Journal

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The effects of acidic pH on the kinetics of Ca2+-ATPase isoforms from intracellular membranes of skeletal muscle, cardiac muscle, cerebellum and blood platelets were studied. At neutral pH, all four Ca2+-ATPase isoforms exhibited similar Ca2+-concentration requirements for half-maximal rates of Ca2+ uptake and ATP hydrolysis. A decrease in the pH from 7.0 to 6.0 promoted a decrease in both the apparent affinity for Ca2+ [increasing half-maximal activation (K0.5)] and the maximal velocity (Vmax) of Ca2+ uptake. With skeletal muscle vesicles these effect were 5 to 10 times smaller than those observed with all the other isoforms. Acidification of the medium from pH 7.0 to 6.5 caused the release of Ca2+ from loaded vesicles and a decrease in the amount of Ca2+ retained by the vesicles at the steady state. With the vesicles derived from skeletal muscle these effects were smaller than for vesicles derived from other tissues. The rate of passive Ca2+ efflux from skeletal and cardiac muscle vesicles, loaded with Ca2+ and diluted in a medium containing none of the ligands of Ca2+-ATPase, was the same at pH 7.0 and 6.0. In contrast, the rate of Ca2+ efflux from cerebellar and platelet vesicles increased 2-fold after acidification of the medium. The effects of DMSO, Mg2+ with Pi and arsenate on the rate of Ca2+ efflux varied among the different preparations tested. The differences became more pronounced when the pH of the medium was decreased from 7.0 to 6.0. It is proposed that the kinetic differences among the Ca2+-ATPase isoforms may reflect different adaptations to cellular acidosis, such as that which occurs during ischaemia.

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Section: Ph-dependence Of Ca 2 + Effluxmentioning

confidence: 99%

Section: Ph-dependence Of Ca 2 + Effluxmentioning

confidence: 99%

Sarco/endoplasmic reticulum Ca2+-ATPase isoforms: diverse responses to acidosis

Wolosker

Rocha

Engelender

et al. 1997

Biochemical Journal

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“…Dimethyl sulfoxide is able to couple the Ca 2+ -ATPase (Inesi & de Meis 1989, de Meis et al 1990, de Meis et al 1980, de Meis 1989 (Table I). Heparin is an uncoupling drug that inhibits both the synthesis and the hydrolysis of ATP and increases the leakage of Ca 2+ through the Ca 2+ -ATPase (de Meis & Suzano 1994, Wolosker & de Meis 1995, Rocha et al 1996. In the presence of 3 µg/ml heparin the vesicles still retained a small amount of Ca 2+ and despite the significant decrease of the ATPase activity, the heat released during the different incubation intervals was similar to that measured with the control without heparin.…”

Section: Heat Production and Atp Synthesismentioning

confidence: 82%

“…In the bibliography, the simultaneous synthesis and hydrolysis of ATP measured in steady state conditions is referred to as the ATP ↔ P i exchange reaction (Hasselbach & Makinose 1961, Barlogie et al 1971, Makinose & Hasselbach 1971, de Meis & Vianna 1979, Inesi 1985, de Meis 1993. Recently (Gould et al 1987, Gould et al 1978, Inesi & de Meis 1989, Galina & de Meis 1991, De Meis et al 1990, de Meis, 1991, de Meis & Suzano 1994, Wolosker & de Meis 1995 it has been shown that during the ATP ↔ P i exchange only part of the Ca 2+ efflux is coupled with the synthesis of ATP. The other part leaks through the Ca 2+ -ATPase without promoting the synthesis of ATP, a process referred to as an uncoupled efflux.…”

Section: Introductionmentioning

confidence: 99%

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Meis

2000

An. Acad. Bras. Ciênc.

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The sarcoplasmic reticulum of skeletal muscle retains a membrane bound Ca 2+ -ATPase which is able to interconvert different forms of energy. A part of the chemical energy released during ATP hydrolysis is converted into heat and in the bibliography it is assumed that the amount of heat produced during the hydrolysis of an ATP molecule is always the same, as if the energy released during ATP cleavage were divided in two non-interchangeable parts: one would be converted into heat, and the other used for Ca 2+ transport. Data obtained in our laboratory during the past three years indicate that the amount of heat released during the hydrolysis of ATP may vary between 7 and 32 Kcal/mol depending on whether or not a transmembrane Ca 2+ gradient is formed across the sarcoplasmic reticulum membrane. Drugs such as heparin and dimethyl sulfoxide are able to modify the fraction of the chemical energy released during ATP hydrolysis which is used for Ca 2+ transport and the fraction which is dissipated in the surrounding medium as heat.

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“…A sarco-endoplasmic reticulum Ca 2+ ATPase (SERCA) pumps Ca 2+ into the ER lumen utilizing the energy derived from ATP hydrolysis. The enzyme is highly conserved among species and its cycle has been extensively studied since 1970 (see Wolosker and de Meis, 1995). Like the PMCA, the SERCA Fig.…”

Section: #\%B!@h!ortb!mentioning

confidence: 99%

Inter-relação do ritmo e da ação de drogas antimaláricas na infecção da malária de roedores

Bagnaresi¹

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The ion calcium is a ubiquitous second messenger, present in all eukaryotic cells. It modulates a vast number of cellular events, such as cell division and differentiation, fertilization, cell volume, decodification of external stimuli. To process this variety of information, the cells display a number of calcium pools, which are capable of mobilization for signaling purposes. Here we review the calcium signaling on lizards red blood cells, an interesting model that has been receiving an increasing notice recently. These cells possess a complex machinery to regulate calcium, and display calcium responses to extracellular agonists. Interestingly, the pattern of calcium handling and response are divergent in different lizard families, which enforces the morphological data to their phylogenetic classification, and suggest the radiation of different calcium signaling models in lizards evolution.

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Ligand-gated channel of the sarcoplasmic reticulum Ca2+ transport ATPase

Cited by 12 publications

References 49 publications

Sarco/endoplasmic reticulum Ca2+-ATPase isoforms: diverse responses to acidosis

Sarco/endoplasmic reticulum Ca2+-ATPase isoforms: diverse responses to acidosis

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Inter-relação do ritmo e da ação de drogas antimaláricas na infecção da malária de roedores

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