The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase

Occlusion of K+ in the Na+/K+-ATPase can be achieved under two conditions: during hydrolysis of ATP, in media with Na+ and Mg2+, after the K+-stimulated dephosphorylation of E2P (physiological route) or spontaneously, after binding of K+ to the enzyme (direct route). We investigated the sidedness of...

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Publicado:	2008
Materias:	Adenosinetriphosphate Enzyme activity Positive ions Rubidium Sodium Deocclusion Incubation sequences Transport sites Enzyme kinetics adenosine triphosphatase (potassium sodium) adenosine triphosphate kidney enzyme magnesium ion phosphate potassium ion rubidium ion sodium ion article cell membrane cell surface dephosphorylation enzyme activity enzyme conformation hydrolysis ion transport nonhuman priority journal swine Animals Binding Sites Kidney Kinetics Ligands Magnesium Potassium Sodium-Potassium-Exchanging ATPase Swine
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v47_n22_p6073_GonzalezLebrero http://hdl.handle.net/20.500.12110/paper_00062960_v47_n22_p6073_GonzalezLebrero
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00062960_v47_n22_p6073_GonzalezLebrero
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spelling	paper:paper_00062960_v47_n22_p6073_GonzalezLebrero2023-06-08T14:30:43Z The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase Adenosinetriphosphate Enzyme activity Positive ions Rubidium Sodium Deocclusion Incubation sequences Transport sites Enzyme kinetics adenosine triphosphatase (potassium sodium) adenosine triphosphate kidney enzyme magnesium ion phosphate potassium ion rubidium ion sodium ion article cell membrane cell surface dephosphorylation enzyme activity enzyme conformation hydrolysis ion transport nonhuman priority journal swine Animals Binding Sites Kidney Kinetics Ligands Magnesium Potassium Rubidium Sodium Sodium-Potassium-Exchanging ATPase Swine Occlusion of K+ in the Na+/K+-ATPase can be achieved under two conditions: during hydrolysis of ATP, in media with Na+ and Mg2+, after the K+-stimulated dephosphorylation of E2P (physiological route) or spontaneously, after binding of K+ to the enzyme (direct route). We investigated the sidedness of spontaneous occlusion and deocclusion of Rb+ in an unsided, purified preparation of Na+/K+-ATPase. Our studies were based on two propositions: (i) in the absence of ATP, deocclusion of K+ and its congeners is a sequential process where two ions are released according to a single file mechanism, both in the absence and in the presence of Mg 2+ plus inorganic orthophosphate (Pi), and (ii) in the presence of Mg2+ plus Pi, exchange of K+ would take place through sites exposed to the extracellular surface of the membrane. The experiments included a double incubation sequence where one of the two Rb+ ions was labeled as 86Rb+. We found that, when the enzyme is in the E2 conformation, the first Rb+ that entered the enzyme in media without Mg2+ and Pi was the last to leave after addition of Mg 2+ plus Pi, and vice-versa. This indicates that spontaneous exchange of Rb+ between E2(Rb2) and the medium takes place when the transport sites are exposed to the extracellular surface of the membrane. Our results open the question if occlusion and deocclusion via the direct route participates in any significant degree in the transport of K+ during the ATPase activity. © 2008 American Chemical Society. 2008 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v47_n22_p6073_GonzalezLebrero http://hdl.handle.net/20.500.12110/paper_00062960_v47_n22_p6073_GonzalezLebrero
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Adenosinetriphosphate Enzyme activity Positive ions Rubidium Sodium Deocclusion Incubation sequences Transport sites Enzyme kinetics adenosine triphosphatase (potassium sodium) adenosine triphosphate kidney enzyme magnesium ion phosphate potassium ion rubidium ion sodium ion article cell membrane cell surface dephosphorylation enzyme activity enzyme conformation hydrolysis ion transport nonhuman priority journal swine Animals Binding Sites Kidney Kinetics Ligands Magnesium Potassium Rubidium Sodium Sodium-Potassium-Exchanging ATPase Swine
spellingShingle	Adenosinetriphosphate Enzyme activity Positive ions Rubidium Sodium Deocclusion Incubation sequences Transport sites Enzyme kinetics adenosine triphosphatase (potassium sodium) adenosine triphosphate kidney enzyme magnesium ion phosphate potassium ion rubidium ion sodium ion article cell membrane cell surface dephosphorylation enzyme activity enzyme conformation hydrolysis ion transport nonhuman priority journal swine Animals Binding Sites Kidney Kinetics Ligands Magnesium Potassium Rubidium Sodium Sodium-Potassium-Exchanging ATPase Swine The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
topic_facet	Adenosinetriphosphate Enzyme activity Positive ions Rubidium Sodium Deocclusion Incubation sequences Transport sites Enzyme kinetics adenosine triphosphatase (potassium sodium) adenosine triphosphate kidney enzyme magnesium ion phosphate potassium ion rubidium ion sodium ion article cell membrane cell surface dephosphorylation enzyme activity enzyme conformation hydrolysis ion transport nonhuman priority journal swine Animals Binding Sites Kidney Kinetics Ligands Magnesium Potassium Rubidium Sodium Sodium-Potassium-Exchanging ATPase Swine
description	Occlusion of K+ in the Na+/K+-ATPase can be achieved under two conditions: during hydrolysis of ATP, in media with Na+ and Mg2+, after the K+-stimulated dephosphorylation of E2P (physiological route) or spontaneously, after binding of K+ to the enzyme (direct route). We investigated the sidedness of spontaneous occlusion and deocclusion of Rb+ in an unsided, purified preparation of Na+/K+-ATPase. Our studies were based on two propositions: (i) in the absence of ATP, deocclusion of K+ and its congeners is a sequential process where two ions are released according to a single file mechanism, both in the absence and in the presence of Mg 2+ plus inorganic orthophosphate (Pi), and (ii) in the presence of Mg2+ plus Pi, exchange of K+ would take place through sites exposed to the extracellular surface of the membrane. The experiments included a double incubation sequence where one of the two Rb+ ions was labeled as 86Rb+. We found that, when the enzyme is in the E2 conformation, the first Rb+ that entered the enzyme in media without Mg2+ and Pi was the last to leave after addition of Mg 2+ plus Pi, and vice-versa. This indicates that spontaneous exchange of Rb+ between E2(Rb2) and the medium takes place when the transport sites are exposed to the extracellular surface of the membrane. Our results open the question if occlusion and deocclusion via the direct route participates in any significant degree in the transport of K+ during the ATPase activity. © 2008 American Chemical Society.
title	The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
title_short	The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
title_full	The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
title_fullStr	The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
title_full_unstemmed	The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase
title_sort	pathway for spontaneous occlusion of rb+ in the na +/k+-atpase
publishDate	2008
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v47_n22_p6073_GonzalezLebrero http://hdl.handle.net/20.500.12110/paper_00062960_v47_n22_p6073_GonzalezLebrero
_version_	1768543447716724736

The pathway for spontaneous occlusion of Rb+ in the Na +/K+-ATPase

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