title: A G-protein-activated inwardly rectifying K+ channel (GIRK4) from human hippocampus associates with other GIRK channels.
abstract: Transcripts of a gene, GIRK4, that encodes for a 419-amino-acid protein and shows high structural similarity to other subfamily members of G-protein-activated inwardly rectifying K+ channels (GIRK) have been identified in the human hippocampus. When expressed in Xenopus oocytes, GIRK4 yielded functional GIRK channels with activity that was enhanced by the stimulation of coexpressed serotonin 1A receptors. GIRK4 potentiated basal and agonist-induced currents mediated by other GIRK channels, possibly because of channel heteromerization. Despite the structural similarity to a putative rat KATP channel, no ATP sensitivity or KATP-typical pharmacology was observed for GIRK4 alone or GIRK4 transfected in conjunction with other GIRK channels in COS-7 cells. In rat brain, GIRK4 is expressed together with three other subfamily members, GIRK1-3, most likely in identical hippocampal neurons. Thus, heteromerization or an unknown molecular interaction may cause the physiological diversity observed within this class of K+ channels.
authors.affiliation: Molecular Neurobiology of Signal Transduction, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Spauschus
authors.forename: K U
authors.initials: KU
authors.lastname: Lentes
authors.forename: E
authors.initials: E
authors.lastname: Wischmeyer
authors.forename: E
authors.initials: E
authors.lastname: Dissmann
authors.forename: C
authors.initials: C
authors.lastname: Karschin
authors.forename: A
authors.initials: A
authors.lastname: Karschin
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019204:GTP-Binding Proteins / Q000378:metabolism; D005796:Genes; D006624:Hippocampus / Q000737:chemistry*; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D051381:Rats; D011985:Receptors, Serotonin / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012701:Serotonin / Q000494:pharmacology; D013045:Species Specificity; D014162:Transfection
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; C490969:Kcnj4 protein, mouse; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins; D011188:Potassium