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NCX1 Surface Expression
Author(s) -
RAHAMIMOFF HANNAH,
REN XIAOYAN,
KIMCHISARFATY CHAVA,
AMBUDKAR SURESH,
KASIR JUDITH
Publication year - 2002
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2002.tb04739.x
Subject(s) - hek 293 cells , cysteine , mutant , transfection , chemistry , gene isoform , microbiology and biotechnology , alanine , biochemistry , transporter , serine , wild type , cell culture , amino acid , gene , biology , enzyme , genetics
A bstract : The rat Na + /Ca 2+ exchanger isoforms of the NCX1 gene have 14 cysteine residues. Each of these cysteines can be mutated individually to alanine or serine without loss of functional expression in transfected HEK293 cells. Yet sequential exchange starting from the amino terminal end of three or more cysteines results in reduced transport activity and surface expression. As more and more cysteines are replaced, transport activity and surface expression decrease in parallel, and the cysteineless mutant exhibits only traces of Na + /Ca 2+ exchange activity and surface expression. No significant differences are detected in the amount of total cell exchanger protein between the wild‐type exchanger and its functional or nonfunctional cysteine mutants. Reduced surface expression of the Na + /Ca 2+ exchanger NCX1 is also observed when HEK293 cells expressing the transporter are treated with cyclosporin A (CsA) or with PSC833. The reductions in transport activity and surface expression are concentration dependent and parallel. No reduction is obtained in the total amount of exchanger protein by CsA or PSC833 treatment, suggesting that the effects of these drugs on NCX1 expression are posttranslational. FK506 and rapamycin treatment of HEK293 cells expressing rat NCX1 isoforms has no effect on transport activity, surface expression, or the total amount of exchanger protein in the transfected cells.