A Ca²⁺ ‐stimulated, Mg²⁺ ‐dependent ATPase activity in subcellular fractions from Schistosoma mansoni

Abstract

A CaZ+-stimulated, MgZ+-dependent ATPase activity was found in subcellular fractions from Schistosoma mansoni. Its specific and relative activities were higher in the heterogeneous cuticle fraction and in the microsomal fraction. The Ko. 5 for ATPase activation by free Ca 2÷ was 0.2q).5 pM. This is the first description of an ATPase activity stimulated by Ca 2+ in the micromolar range in S. mansoni.(Ca 2+ + Mga+)-ATPase; Ca2+; Subcellular fraction; Microsome; (Schistosoma mansoni)

PCA3 noncoding RNA is involved in the control of prostate-cancer cell survival and modulates androgen receptor signaling

“…The homogenate was centrifuged as described elsewhere [17] to obtain four pellets (P1, P2, P3 and P4), which sedimented respectively at 300 × g (5 min), 1000 × g (10 min), 8000 × g (10 min) and 100,000 × g (60 min). Fraction P1 contained mainly nuclei and some vesicles.…”

Schistosoma mansoni Ca2+-ATPase SMA2 Restores Viability to Yeast Ca2+-ATPase-deficient Strains and Functions in Calcineurin-mediated Ca2+Tolerance

“…Gradients were fractionated from the top to bottom, manually, in 1-ml aliquots (fractions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] that were stored at Ϫ70°C.…”

“…Ca 2ϩ -stimulated, Mg 2ϩ -dependent ATPase activity has been found in S. mansoni tissue homogenates (13) and microsomal fractions (14), which is coupled with an active transport of calcium (15). However, a correlation between this ATPase activity and specific Ca 2ϩ -ATPase isoforms has not been established.…”

Control of calcium homeostasis in Schistosoma mansoni

“…In this way we may propose that the presence of sarcoplasmic reticulum calcium stores, with both SERCA and RyR, is essencial to support worm contraction. In Table we 23.3 ± 4.7 11.1 ± 3.9 4.4 ± 0.9 7.5 ± 1.6 P 4 34.5 ± 3.0 26.7 ± 6.4 *51.8 ± 6.7 *45.0 ± 5.0 n = 7 n = 7 n = 7 n = 6 (Ca 2+ -Mg 2+ )-ATPase activity corresponds to the Mg 2+ -dependent ATPase that is stimulated by micromolar concentrations of free calcium and that has been shown to be responsible for active calcium pumping (Cunha et al 1988). The thapsigargin-sensitive (TgS) activity was calculated subtracting the thapsigargin-resistant (TgR) activity (measured in the presence of 1 µM thapsigargin) from the total (Ca 2+ -Mg 2+ )-ATPase activity (measured in the absence of thapsigargin).…”

“…The homogenate was centrifuged to obtain four pellets (P 1 , P 2 , P 3 , P 4 ) sedimenting respectively at 300 g av (5 min); 1000 g av (10 min); 8000 g av (10 min) and 100,000 g av (1 h). These fractions have been previously characterized by electronic microscopy (Cunha et al 1988) as heterogeneous (P 1 ), nuclear (P 2 ), mitochondrial (P 3 ) and microsomal (P 4 ).…”