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Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development

The sodium/potassium pump, Na(+),K(+)-ATPase, is generally understood to function as a heterodimer of two subunits, a catalytic α subunit and a noncatalytic, glycosylated β subunit. Recently, a putative third subunit, the γ subunit, was cloned. This small protein (6.5 kD) coimmunoprecipitates with t...

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Detalles Bibliográficos
Autores principales: Jones, D. Holstead, Davies, Tyler C., Kidder, Gerald M.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1997
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132623/
https://www.ncbi.nlm.nih.gov/pubmed/9396759
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author Jones, D. Holstead
Davies, Tyler C.
Kidder, Gerald M.
author_facet Jones, D. Holstead
Davies, Tyler C.
Kidder, Gerald M.
author_sort Jones, D. Holstead
collection PubMed
description The sodium/potassium pump, Na(+),K(+)-ATPase, is generally understood to function as a heterodimer of two subunits, a catalytic α subunit and a noncatalytic, glycosylated β subunit. Recently, a putative third subunit, the γ subunit, was cloned. This small protein (6.5 kD) coimmunoprecipitates with the α and β subunits and is closely associated with the ouabain binding site on the holoenzyme, but its function is unknown. We have investigated the expression of the γ subunit in preimplantation mouse development, where Na(+),K(+)-ATPase plays a critical role as the driving force for blastocoel formation (cavitation). Using reverse transcriptase-polymerase chain reaction, we demonstrated that the γ subunit mRNA accumulates continuously from the eight-cell stage onward and that it cosediments with polyribosomes from its time of first appearance. Confocal immunofluorescence microscopy revealed that the γ subunit itself accumulates and is localized at the blastomere surfaces up to the blastocyst stage. In contrast with the α and β subunits, the γ subunit is not concentrated in the basolateral surface of the polarized trophectoderm layer, but is strongly expressed at the apical surface as well. When embryos were treated with antisense oligodeoxynucleotide complementary to the γ subunit mRNA, ouabain-sensitive K(+) transport (as indicated by (86)Rb(+) uptake) was reduced and cavitation delayed. However, Na(+),K(+)-ATPase enzymatic activity was unaffected as determined by a direct phosphorylation assay (“back door” phosphorylation) applied to plasma membrane preparations. These results indicate that the γ subunit, although not an integral component of Na(+),K(+)-ATPase, is an important determinant of active cation transport and that, as such, its embryonic expression is essential for blastocoel formation in the mouse.
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spelling pubmed-21326232008-05-01 Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development Jones, D. Holstead Davies, Tyler C. Kidder, Gerald M. J Cell Biol Article The sodium/potassium pump, Na(+),K(+)-ATPase, is generally understood to function as a heterodimer of two subunits, a catalytic α subunit and a noncatalytic, glycosylated β subunit. Recently, a putative third subunit, the γ subunit, was cloned. This small protein (6.5 kD) coimmunoprecipitates with the α and β subunits and is closely associated with the ouabain binding site on the holoenzyme, but its function is unknown. We have investigated the expression of the γ subunit in preimplantation mouse development, where Na(+),K(+)-ATPase plays a critical role as the driving force for blastocoel formation (cavitation). Using reverse transcriptase-polymerase chain reaction, we demonstrated that the γ subunit mRNA accumulates continuously from the eight-cell stage onward and that it cosediments with polyribosomes from its time of first appearance. Confocal immunofluorescence microscopy revealed that the γ subunit itself accumulates and is localized at the blastomere surfaces up to the blastocyst stage. In contrast with the α and β subunits, the γ subunit is not concentrated in the basolateral surface of the polarized trophectoderm layer, but is strongly expressed at the apical surface as well. When embryos were treated with antisense oligodeoxynucleotide complementary to the γ subunit mRNA, ouabain-sensitive K(+) transport (as indicated by (86)Rb(+) uptake) was reduced and cavitation delayed. However, Na(+),K(+)-ATPase enzymatic activity was unaffected as determined by a direct phosphorylation assay (“back door” phosphorylation) applied to plasma membrane preparations. These results indicate that the γ subunit, although not an integral component of Na(+),K(+)-ATPase, is an important determinant of active cation transport and that, as such, its embryonic expression is essential for blastocoel formation in the mouse. The Rockefeller University Press 1997-12-15 /pmc/articles/PMC2132623/ /pubmed/9396759 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Jones, D. Holstead
Davies, Tyler C.
Kidder, Gerald M.
Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title_full Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title_fullStr Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title_full_unstemmed Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title_short Embryonic Expression of the Putative γ Subunit of the Sodium Pump Is Required for Acquisition of Fluid Transport Capacity during Mouse Blastocyst Development
title_sort embryonic expression of the putative γ subunit of the sodium pump is required for acquisition of fluid transport capacity during mouse blastocyst development
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2132623/
https://www.ncbi.nlm.nih.gov/pubmed/9396759
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