title: Insights in KIR2.1 channel structure and function by an evolutionary approach; cloning and functional characterization of the first reptilian inward rectifier channel KIR2.1, derived from the California kingsnake (Lampropeltis getula californiae).
abstract: Potassium inward rectifier KIR2.1 channels contribute to the stable resting membrane potential in a variety of muscle and neuronal cell-types. Mutations in the KIR2.1 gene KCNJ2 have been associated with human disease, such as cardiac arrhythmias and periodic paralysis. Crystal structure and homology modelling of KIR2.1 channels combined with functional current measurements provided valuable insights in mechanisms underlying channel function. KIR2.1 channels have been cloned and analyzed from all main vertebrate phyla, except reptilians. To address this lacuna, we set out to clone reptilian KIR2.1 channels. Using a degenerated primer set we cloned the KCNJ2 coding regions from muscle tissue of turtle, snake, bear, quail and bream, and compared their deduced amino acid sequences with those of KIR2.1 sequences from 26 different animal species obtained from Genbank. Furthermore, expression constructs were prepared for functional electrophysiological studies of ectopically expressed KIR2.1 ion channels. In general, KCNJ2 gene evolution followed normal phylogenetic patterns, however turtle KIR2.1 ion channel sequence is more homologues to avians than to snake. Alignment of all 31 KIR2.1 sequences showed that all disease causing KIR2.1 mutations, except V93I, V123G and N318S, are fully conserved. Homology models were built to provide structural insights into species specific amino acid substitutions. Snake KIR2.1 channels became expressed at the plasmamembrane and produced typical barium sensitive (IC50 ∼6μM) inward rectifier currents.
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands. Electronic address: M.J.C.Houtman@umcutrecht.nl.
authors.forename: Marien J C
authors.initials: MJ
authors.lastname: Houtman
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands.
authors.forename: Sanne M
authors.initials: SM
authors.lastname: Korte
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ji
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: Kok
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Vos
authors.affiliation: Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria.
authors.forename: Anna
authors.initials: A
authors.lastname: Stary-Weinzinger
authors.affiliation: Department of Medical Physiology, DH&L, UMC Utrecht, The Netherlands.
authors.forename: Marcel A G
authors.initials: MA
authors.lastname: van der Heyden
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001717:Birds / Q000235:genetics*; D003001:Cloning, Molecular; D017812:Colubridae / Q000235:genetics*; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D006801:Humans; D015640:Ion Channel Gating / Q000235:genetics*; D008969:Molecular Sequence Data; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry / Q000502:physiology*; D013045:Species Specificity; D013329:Structure-Activity Relationship
chemical_list: C489461:Kir2.1 channel; D024661:Potassium Channels, Inwardly Rectifying
keywords: Andersen–Tawil disease; Electrophysiology; Ion channel; K(IR)2.1; Molecular modelling; Phylogeny