ISSN:
1573-4919
Keywords:
(Ca2+, Mg2+)-ATPase
;
calcium transport
;
ATP ⇋ Pi exchange
;
plasma membrane
;
AS-30D hepatocarcinoma
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Plasma membrane fractions from normal, regenerating liver and the AS-30D ascites hepatocarcinoma exhibited a high degree of enrichment when a set of plasma membrane enzyme markers were studied in comparison to the ones associated to the mitochondrial and cytosolic compartments. While the (Ca2+, Mg2+)-ATPase observed for the plasma membrane fraction isolated from normal liver showed an activity of 1.2 µmoles/mg/min, the regenerating liver and the AS-30D plasma membrane fractions presented a much lower ATPase activity (0.3 and 0.22 µmoles/mg/min respectively). Despite the differences in ATPase activity observed between models, the plasma membrane fraction from the AS-30D hepatocarcinoma presented a calcium transport activity similar to the value observed for the normal system (5.9 and 5.5 nmoles Ca2+/mg/10min, respectively). Interestingly, the ATP ⇋ Pi exchange experiments carried out with the different plasma membrane fractions revealed that the (Ca2+, Mg2+)-ATPase contained in the plasma membrane from the AS-30D cells shows an exchange activity of 26 nmoles ATP ⇋ Pi/mg/min, similar to the one observed for the enzyme from normal liver (30 nmoles ATP ⇋ Pi/mg/min). Our results suggest that the plasma membrane from the transformed model presents a more efficient mechanism to regulate the movement of calcium through the calcium pump, with an optimum expenditure of energy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00230808
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