The interaction of potassium ions and ATP on the sodium pump of resealed red cell ghosts.

Eisner, David; Richards, Donald E.

doi:10.1113/jphysiol.1981.sp013917

Cited by 51 publications

(38 citation statements)

References 32 publications

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“…Likewise the higher K 0.5 (K ϩ ) value found for the mutant relative to wild type under these conditions (supplemental Fig. S2) may be accounted for by the enhancement of the rate-limiting [K 2 ]E 2 3 E 1 step (44). These effects of the L99F mutation are very similar to the observations with E329Q using the same assay of ATP hydrolysis at 50 M ATP (18).…”

Section: Resultssupporting

confidence: 75%

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Einholm

Andersen

Vilsen

2007

Journal of Biological Chemistry

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Twenty-six point mutations were introduced into the N-terminal and middle parts of transmembrane segment M1 of the Na ؉ ,K ؉ -ATPase and its cytosolic extension. None of the alterations to charged and polar residues in the N-terminal part of M1 and its cytosolic extension had any major effect on the cation binding properties, thus rejecting the hypothesis that these residues are involved in cation selectivity. By contrast, specific residues in the middle part of M1, particularly Leu 99 , were found critical to K ؉ interaction of the enzyme. Hence, mutation L99A reduced the affinity for K ؉ activation of E 2 P dephosphorylation 17-fold, and L99F reduced the equilibrium level of the K

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Section: Resultssupporting

confidence: 75%

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Einholm

Andersen

Vilsen

2007

Journal of Biological Chemistry

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“…This is analogous to the effect on the apparent affinity for external K+ caused by ATP-induced acceleration of the E2(K)+El transition [29].…”

Section: Of Expressed E~wousmentioning

confidence: 65%

Functional consequences of alterations to Pro³²⁸ and Leu³³² located in the 4th transmembrane segment of the α‐subunit of the rat kidney Na⁺,K⁺‐ATPase

Vilsen

1992

FEBS Letters

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Site‐specific mutagenesis was used to analyse the functional roles of the residues Pro328 and Leu332 located in the conserved PEGLL motif of the predicted transmembrane helix M4 in the α1‐subunit of the ouabain resistant rat kidney Na+,K+‐ATPase. cDNAs encoding either of the Na+,K+‐ATPase mutants Pro328→Ala and Leu332→Ala, and wild type, were cloned into the expression vector pMT2 and transfected into COS‐1 cells. Ouabain‐resistant clones growing in the presence of 10 μM ouabain were isolated, and the Na+, K+, ATP and pH dependencies of the Na+,K+‐ATPase activity measured in the presence of 10 μM ouabain were analysed. Under these conditions the exogenous expressed Na+,K+‐ATPase contributed more than 95% of the Na+,K+‐ATPase activity. The Pro328→Ala mutant displayed a reduced apparent affinity for Na+ (K 0.5 (Na+) 13.04 mM), relative to the wild type (K 0.5 (Na+) 7.13 mM). By contrast, the apparent affinity for Na+ displayed by the Leu 332→Ala mutant was increased (K 0.5 (Na+) 3.92 mM). Either of the mutants exhibited lower apparent affinity for K+ relative to the wild type (K 0.5 (K+) 2.46 mM for Pro328→Ala and 1.97 mM for Leu332→Ala, compared with 0.78 mM for wild type). Both mutants exhibited higher apparent affinity for ATP than the wild type (K 0.5 (ATP) 0.086 mM for Pro328→Ala and 0.042 mM for Leu332→Ala, compared with 0.287 mM for wild type). The influence of pH was in accordance with an acceleration of the E2 (K)→E1 transition in the mutants relative to the wild type. These data are consistent with a role of Pro328 and Leu332 in the stabilization of the E2 form and of Pro328 in Na+ binding. The possible role of the mutated residues in K+ binding is discussed.

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“…A ␥-mediated decrease in KЈ ATP could explain this increase in KЈ 0.5 for K ϩ because, as a first approximation, ATP and K ϩ affinities are inversely related (20). However, that result may be confounded by the use of cRNA synthesized using the original sequence for rat ␥ (5).…”

Section: Discussionmentioning

confidence: 99%

Expression and Functional Role of the γ Subunit of the Na,K-ATPase in Mammalian Cells

Therien¹,

Karlish²,

Blostein³

1999

Journal of Biological Chemistry

125

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The functional role of the ␥ subunit of the Na,KATPase was studied using rat ␥ cDNA-transfected HEK-293 cells and an antiserum (␥C33) specific for ␥. Although the sequence for ␥ was verified and shown to be larger (7237 Da) Overall, our data demonstrate that ␥ is a tissue (kidney)-specific regulator of the Na,K-ATPase that can increase the apparent affinity of the enzyme for ATP in a manner that is reversible by anti-␥ antiserum.The Na,K-ATPase is the sodium pump protein responsible for maintaining the electrochemical gradient present across the membranes of most animal cells (1). It consists of at least two subunits, ␣ and ␤, each of which exists as one of several isoforms

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The interaction of potassium ions and ATP on the sodium pump of resealed red cell ghosts.

Cited by 51 publications

References 32 publications

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Functional consequences of alterations to Pro³²⁸ and Leu³³² located in the 4th transmembrane segment of the α‐subunit of the rat kidney Na⁺,K⁺‐ATPase

Expression and Functional Role of the γ Subunit of the Na,K-ATPase in Mammalian Cells

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The interaction of potassium ions and ATP on the sodium pump of resealed red cell ghosts.

Cited by 51 publications

References 32 publications

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Importance of Leu99 in Transmembrane Segment M1 of the Na+,K+-ATPase in the Binding and Occlusion of K+

Functional consequences of alterations to Pro328 and Leu332 located in the 4th transmembrane segment of the α‐subunit of the rat kidney Na+,K+‐ATPase

Expression and Functional Role of the γ Subunit of the Na,K-ATPase in Mammalian Cells

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Functional consequences of alterations to Pro³²⁸ and Leu³³² located in the 4th transmembrane segment of the α‐subunit of the rat kidney Na⁺,K⁺‐ATPase