Altered coupling states between calcium transport and (Ca2+, Mg2+)-ATPase in the AS-30D ascites hepatocarcinoma plasma membrane.

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 mumoles/mg/min, the regenerating liver and the AS-30D plasma membrane fractions presented a much lower ATPase activity (0.3 and 0.22 mumoles/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/10 min, respectively). Interestingly, the ATP in equilibrium with 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 in equilibrium with Pi/mg/min, similar to the one observed fo the enzyme from normal liver (30 nmoles ATP in equilibrium with 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.

• Authors: J Mas-Oliva, R Pérez-Montfort, M Cárdenas-García, M Rivas-Duro
• Journal: Molecular and cellular biochemistry (Mol Cell Biochem) Vol. 100 Issue 1 Pg. 39-50 (Jan 16 1991) ISSN: 0300-8177 [Print] Netherlands
• PMID: 1828860 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Detergents
• Inosine Triphosphate
• Vanadates
• Polyethylene Glycols
• Sodium Chloride
• Cytidine Triphosphate
• Guanosine Triphosphate
• Adenosine Triphosphate
• Octoxynol
• Ca(2+) Mg(2+)-ATPase
• Calcium-Transporting ATPases
• Calcium

Topics

• Adenosine Triphosphate (metabolism)
• Animals
• Biological Transport, Active
• Ca(2+) Mg(2+)-ATPase (metabolism)
• Calcium (metabolism)
• Calcium-Transporting ATPases (metabolism)
• Cell Membrane (enzymology, metabolism)
• Cell Transformation, Neoplastic (metabolism)
• Cytidine Triphosphate (metabolism)
• Detergents
• Guanosine Triphosphate (metabolism)
• Hydrogen-Ion Concentration
• Inosine Triphosphate (metabolism)
• Kinetics
• Liver (enzymology)
• Liver Neoplasms, Experimental
• Liver Regeneration
• Male
• Octoxynol
• Polyethylene Glycols
• Rats
• Rats, Inbred Strains
• Sodium Chloride (pharmacology)
• Vanadates (pharmacology)