title: Topologic investigation of the NCKX2 Na+/Ca2+-K+ exchanger alpha-repeats.
abstract: Algorithms suggest that NCKX proteins consist of an N-terminal signal peptide and 11 transmembrane segments divided in two groups of 5 and 6, respectively, separated by a large cytoplasmic loop. This predicted topology places the NCKX alpha-repeats with the same orientation in the plasma membrane. Using thiol-specific drug treatment and site-directed disulfide mapping, we have investigated the orientation of the NCKX2 alpha-repeats. Our results suggest that the NCKX2 alpha-repeats have an antiparallel orientation in the plasma membrane. In addition, these experiments suggest that the alpha-repeats are found in close proximity in the mature configuration of the protein.
authors.affiliation: Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive, N.W. Calgary, Alberta, T2N 4N1, Canada.
authors.forename: Tashi G
authors.initials: TG
authors.lastname: Kinjo
authors.forename: Robert T
authors.initials: RT
authors.lastname: Szerencsei
authors.forename: Paul P M
authors.initials: PP
authors.lastname: Schnetkamp
mesh_terms: D000465:Algorithms; D004220:Disulfides / Q000737:chemistry; D011487:Protein Conformation; D019831:Sodium-Calcium Exchanger / Q000737:chemistry*
chemical_list: D004220:Disulfides; D019831:Sodium-Calcium Exchanger; C074530:potassium-dependent sodium-calcium exchanger