title: [Functional coupling of the calcium pump and glucose 6-phosphatase activity in liver microsomes: preliminary results].
abstract: The addition of G-6-Pi to the incubation system for MgATP-dependent calcium transport in liver microsomes results in a marked stimulation of Ca2+ uptake. At physiological pH values (7.2-7.4), the G-6-Pi stimulated calcium uptake is maximal and equals that obtained with oxalate at pH 6.8. In the system for the G-6-Pi-stimulated calcium uptake, G-6-Pi is actively hydrolyzed by the glucose 6-phosphatase activity of liver microsomes. Such an activity is not influenced by the concomitant calcium uptake. After the incubation of the system for the MgATP-dependent microsomal calcium transport in the presence of G-6-Pi, Pi and calcium are found in equal concentrations, on a molar base, in the recovered microsomal fraction. These results are interpreted in the light of a possible cooperative activity between the energy-dependent calcium pump of liver microsomes and the glucose 6-phosphatase multicomponent system.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D005952:Glucose-6-Phosphatase / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010070:Oxalates / Q000494:pharmacology; D019815:Oxalic Acid; D010710:Phosphates / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D010070:Oxalates; D010710:Phosphates; D000255:Adenosine Triphosphate; D019815:Oxalic Acid; D005952:Glucose-6-Phosphatase; D002118:Calcium
vernacular_title: Funzionamento accoppiato delle pompe del calcio e dell'attivita' glucoso 6-fosfatasica nei microsomi epatici: risultati preliminari.