title: Molecular characterization, functional expression and tissue distribution of a second NCKX Na+/Ca2+ -K+ exchanger from Drosophila.
abstract: The Na+/Ca2+ -K+ exchanger (NCKX) utilizes the inward Na+ gradient and the outward K+ gradient to promote Ca2+ extrusion from cells. Here, we have characterized a second NCKX from Drosophila. Based on its chromosomal location (X chromosome) we have named it Ncxk-x. Three splice variants were isolated with three distinct N-terminal sequences. NCKX-X differs from NCKX proteins described so far in other species by lacking an N-terminal signal peptide. Heterologous expression of the respective cDNA's resulted in NCKX-X protein expression and K+ -dependent Na+/Ca2+ exchange activity for two of the three splice variants. Transcript localization of Nckx-x was investigated and compared with that previously described by us for Nckx30C.
authors.affiliation: Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive, NW, Alta., Canada T2N 4N1.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Winkfein
authors.forename: Bret
authors.initials: B
authors.lastname: Pearson
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ward
authors.forename: Robert T
authors.initials: RT
authors.lastname: Szerencsei
authors.forename: Nansi J
authors.initials: NJ
authors.lastname: Colley
authors.forename: Paul P M
authors.initials: PP
authors.lastname: Schnetkamp
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009420:Nervous System / Q000196:embryology / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D017433:Protein Structure, Secondary; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D019831:Sodium-Calcium Exchanger; C074530:potassium-dependent sodium-calcium exchanger; D012964:Sodium; D011188:Potassium; D002118:Calcium