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PMID:17392381

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Citation

Matsushita, M, Sano, Y, Yokoyama, S, Takai, T, Inoue, H, Mitsui, K, Todo, K, Ohmori, H and Kanazawa, H (2007) Loss of calcineurin homologous protein-1 in chicken B lymphoma DT40 cells destabilizes Na+/H+ exchanger isoform-1 protein. Am. J. Physiol., Cell Physiol. 293:C246-54

Abstract

NHE1/SLC9A1 is a ubiquitous isoform of vertebrate Na(+)/H(+) exchangers (NHEs) functioning in maintaining intracellular concentrations of Na(+) and H(+) ions. Calcineurin homologous protein-1 (CHP1) binds to the hydrophilic region of NHE1 and regulates NHE1 activity but reportedly does not play a role in translocating NHE1 from the endoplasmic reticulum to the plasma membrane. However, an antiport function of NHE1 requiring CHP1 remains to be clarified. Here we established CHP1-deficient chicken B lymphoma DT40 cells by gene targeting to address CHP1 function. CHP1-deficient cells showed extensive decreases in Na(+)/H(+) activities in intact cells. Although NHE1 mRNA levels were not affected, NHE1 protein levels were significantly reduced not only in the plasma membrane but in whole cells. The expression of a CHP1 transgene in CHP1-deficient cells rescued NHE1 protein expression. Expression of mutant forms of CHP1 defective in Ca(2+) binding or myristoylation also partially decreased NHE1 protein levels. Knockdown of CHP1 also caused a moderate decrease in NHE1 protein in HeLa cells. These data indicate that CHP1 primarily plays an essential role in stabilization of NHE1 for reaching of NHE1 to the plasma membrane and its exchange activity.

Links

PubMed Online version:10.1152/ajpcell.00464.2006

Keywords

Amiloride/analogs & derivatives; Amiloride/pharmacology; Animals; Calcium/metabolism; Calcium-Binding Proteins/deficiency; Calcium-Binding Proteins/genetics; Calcium-Binding Proteins/metabolism; Cation Transport Proteins/genetics; Cation Transport Proteins/metabolism; Chickens; Down-Regulation; Gene Deletion; HeLa Cells; Humans; Lymphoma, B-Cell/metabolism; Lymphoma, B-Cell/pathology; Mutation; Myristic Acid/metabolism; Opossums; Protein Binding; Protein Isoforms/metabolism; Protein Processing, Post-Translational; RNA Interference; RNA, Messenger/metabolism; RNA, Small Interfering/genetics; RNA, Small Interfering/metabolism; Sodium/metabolism; Sodium-Hydrogen Antiporter/antagonists & inhibitors; Sodium-Hydrogen Antiporter/genetics; Sodium-Hydrogen Antiporter/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

CHICK:Q1PS52

located_in

GO:0005886: plasma membrane

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

CHICK:CHP1

involved_in

GO:0032417: positive regulation of sodium:proton antiporter activity

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

CHICK:CHP1

involved_in

GO:0050821: protein stabilization

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

CHICK:CHP1

involved_in

GO:0071468: cellular response to acidic pH

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

CHICK:CHP1

involved_in

GO:0090314: positive regulation of protein targeting to membrane

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

CHICK:Q1PS52

involved_in

GO:0071468: cellular response to acidic pH

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

CHICK:Q1PS52

part_of

GO:0005886: plasma membrane

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

CHICK:Q1PS52

enables

GO:0015385: sodium:proton antiporter activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

CHICK:Q1PS52

involved_in

GO:0036376: sodium ion export across plasma membrane

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

See also

References

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