NCX1 Na/Ca exchanger splice variants in pancreatic islet cells.
In the rat pancreatic beta-cell, Na/Ca exchange displays a quite high capacity. The cell is equipped with two alternatively spliced Na/Ca exchanger-1 (NCX1) isoforms, namely NCX1.3 and NCX1.7. To examine the existence of a possible functional difference between these splice variants, they were cloned, together with the heart variant NCX1.1, and expressed in human embryonic kidney-293 (HEK293) and Chinese hamster ovary (CHO) cells. In these two systems, the three splice variants showed a comparable level of intracellular Na+ (Na+(i))-dependent extracellular Ca2+(Ca2+(o)) uptake. Different levels of NCX1.3 and NCX1.7 transcripts were found in four rodent species, together with a marked interspecies difference in Na/Ca exchange activity. Three additional splice variants were found (NCX1.2, NCX1.9 and NCX1.13) in guinea-pigs, hamsters and mice, again in different proportions. Our data provide evidence for the activity of the three NCX1 splice variants. They also show the existence of a differential and species-specific transcription pattern of NCX1 gene products in pancreatic islet cells.
Van Eylen
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Laboratory of Pharmacology, Brussels University School of Medicine, Bâtiment GE, 808 route de Lennik, B-1070 Brussels, Belgium.
Bollen
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Herchuelz
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D018929:Cell Culture Techniques; D006224:Cricetinae; D006168:Guinea Pigs; D006801:Humans; D007515:Islets of Langerhans / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D051381:Rats; D019831:Sodium-Calcium Exchanger / Q000737:chemistry / Q000235:genetics*; D013045:Species Specificity; D014162:Transfection
D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; D002118:Calcium