Subunit requirements for expression of functional sodium pumps in yeast cells

Scheiner‐Bobis, Georgios; Farley, Robert A.

doi:10.1016/0005-2736(94)90157-0

Cited by 48 publications

(40 citation statements)

References 44 publications

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“…Previous studies of the ␥ subunit failed to uncover a channel-inducing activity in Xenopus oocytes (8) or yeast (12).…”

Section: Discussionmentioning

confidence: 99%

“…The exact role of the ␥ subunit in Na,K-ATPase function is unknown, although its necessity for both ATPase and transport activity has been questioned experimentally (10)(11)(12). For example, detergent extraction of the ␥ subunit from purified Na,K-ATPase does not affect the ATPase activity of the enzyme (10).…”

mentioning

confidence: 99%

“…For example, detergent extraction of the ␥ subunit from purified Na,K-ATPase does not affect the ATPase activity of the enzyme (10). Moreover, expression studies have demonstrated that the ␣ and ␤ subunits are sufficient for the functional expression of Na,K-ATPase activity and expression of the ␥ subunit with the rat ␣1 and ␤1 subunits in yeast does not affect the affinities of the enzyme for Na ϩ or ouabain (12). Recently, however, it was shown that the ␥ subunit can modify the voltage dependence of K ϩ activation of the ␣1␤1 isozyme when expressed in Xenopus oocytes (8).…”

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confidence: 99%

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The gamma subunit of the Na,K-ATPase induces cation channel activity

Minor

Sha

Nichols

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

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The ␥ subunit of the Na,K-ATPase is a hydrophobic protein of approximately 10 kDa. The ␥ subunit was expressed in Sf-9 insect cells and Xenopus oocytes to ascertain its role in Na,K-ATPase function. Immunoblotting has shown that the ␥ subunit is expressed in Sf-9 cells infected with recombinant baculovirus containing the cDNA for the human ␥ subunit. Confocal microscopy demonstrates that the ␥ subunit can be delivered to the plasma membrane of Sf-9 cells independently of the other Na,K-ATPase subunits and that ␥ colocalizes with ␣1 when these proteins are coexpressed. When Sf-9 cells were coinfected with ␣1 and ␥, antibodies to the ␥ subunit were able to coimmunoprecipitate the ␣1 subunit, suggesting that ␥ is able to associate with ␣1. The ␥ subunit is a member of a family of single-pass transmembrane proteins that induces ion f luxes in Xenopus oocytes. Evidence that the ␥ subunit is a functional component was supported by experiments showing ␥-induced cation channel activity when expressed in oocytes and increases in Na ؉ and K ؉ uptake when expressed in Sf-9 cells.

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“…Previous studies of the ␥ subunit failed to uncover a channel-inducing activity in Xenopus oocytes (8) or yeast (12).…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The gamma subunit of the Na,K-ATPase induces cation channel activity

Minor

Sha

Nichols

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

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“…Known as the ␥ subunit, it is not present in all tissues, and its role in the Na,K-ATPase has long been an enigma (15)(16)(17). As an ancillary subunit it is likely to play a modulatory role.…”

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confidence: 99%

The γ Subunit Modulates Na+ and K+Affinity of the Renal Na,K-ATPase

Arystarkhova

Wetzel

Asinovski

et al. 1999

Journal of Biological Chemistry

185

186

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The Na؉ ,K ؉ -ATPase catalyzes the active transport of ions. It has two necessary subunits, ␣ and ␤, but in kidney it is also associated with a 7.4-kDa protein, the ␥ subunit. Stable transfection was used to determine the effect of ␥ on Na,K-ATPase properties. When isolated from either kidney or transfected cells, ␣␤␥ had lower affinities for both Na ؉ and K ؉ than ␣␤. A post-translational modification of ␥ selectively eliminated the effect on Na ؉ affinity, suggesting three configurations (␣␤, ␣␤␥, and ␣␤␥*) conferring different stable properties to Na,K-ATPase. In the nephron, segment-specific differences in Na ؉ affinity have been reported that cannot be explained by the known ␣ and ␤ subunit isoforms of Na,K-ATPase. Immunofluorescence was used to detect ␥ in rat renal cortex. Cortical ascending limb and some cortical collecting tubules lacked ␥, correlating with higher Na ؉ affinities in those segments reported in the literature. Selective expression in different segments of the nephron is consistent with a modulatory role for the ␥ subunit in renal physiology.

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“…As expression systems for the mutated sequence, several assays are applied: cRNA injection into Xenopus oocytes is very useful for electrophysiological studies (Horisberger et al 1991;Vasilets et al 1991), while for biochemical studies overexpression of ATPases in yeast (Scheiner-Bobis and Farley 1994;Pedersen et al 1996) or insect cell lines (Blanco et al 1995;Gatto et al 2001) is convenient. In such cell lines the use of a baculovirus infection system was very successful for the examination of the H,K-ATPase (Klaassen et al 1993) and the Na,K-ATPase (Gatto et al 2001).…”

Section: Probing Crucial Amino Acidsmentioning

confidence: 99%

Structure-function relationship in P-type ATPases—a biophysical approach

Apell

Reviews of Physiology, Biochemistry and Pharmacology

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P-type ATPases are a large family of membrane proteins that perform active ion transport across biological membranes. In these proteins the energy-providing ATP hydrolysis is coupled to ion-transport that builds up or maintains the electrochemical potential gradients of one or two ion species across the membrane. P-type ATPases are found in virtually all eukaryotic cells and also in bacteria, and they are transporters of a broad variety of ions. So far, a crystal structure with atomic resolution is available only for one species, the SR Ca-ATPase. However, biochemical and biophysical studies provide an abundance of details on the function of this class of ion pumps. The aim of this review is to summarize the results of preferentially biophysical investigations of the three best-studied ion pumps, the Na,K-ATPase, the gastric H,K-ATPase, and the SR Ca-ATPase, and to compare functional properties to recent structural insights with the aim of contributing to the understanding of their structure-function relationship.

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Subunit requirements for expression of functional sodium pumps in yeast cells

Cited by 48 publications

References 44 publications

The gamma subunit of the Na,K-ATPase induces cation channel activity

The gamma subunit of the Na,K-ATPase induces cation channel activity

The γ Subunit Modulates Na+ and K+Affinity of the Renal Na,K-ATPase

Structure-function relationship in P-type ATPases—a biophysical approach

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