California Institute of Technology

Norman Davidson

Henry A Lester

Nancy F Lim

Wolfgang Schreibmayer

Nathan Dascal

Paulo Kofuji

Compositions and methods are provided for producing functional mammalian inward rectifier, G-protein activated potassium channels (Kir3.0 channels). A channel is a multimeric protein comprising one or more Kir3.0 polypeptides, e.g. Kir3.1, Kir3.2, etc., where the polypeptides may be from the same or different species. The functional channel has the distinctive features of an anomalous rectifier, in that it conducts inward but not outward Kcurrent; it is blocked by low concentrations of extracellular Csor Ba; and the conductance of the channel does not depend solely on voltage, but on (E-E). The ability of the channel to conduct inward Kcurrent is modulated by G-proteins, particularly G-proteins of the G/Gfamily. A number of mammalian cell surface receptors activate G-proteins as a consequence of specific ligand binding. The signal transduction from receptor to Kir3.0 channel is therefore coupled through G-protein intermediates. The functional Kir3.0 channels are useful in drug screening assays directed to modulation of cellular electrophysiology. Nucleic acids encoding Kir3.0 polypeptides are useful for expression of the gene product, and for identification of homologous genes from other species, as well as other members of the same family of proteins. Expression of the nucleic acids in a heterologous cell, e.g. Xenopus oocyte, confers the ability to cause a change in potassium flow in response to G-protein activation.

Method of inhibiting inward rectifier, G-protein activated, mammalian, potassium channels and uses thereof

This invention provides isolated nucleic acid molecules which encode inward rectifier, G-protein activated, mammalian, potassium KGA channel. This invention also provides a nucleic acid molecule of at least 15 nucleotides capable of specifically hybridizing with the above nucleic acid molecule. This invention further provides a vector comprising the isolated nucleic acid molecules which encode inward rectifier, G-protein activated, mammalian, potassium KGA channel. This invention provides a host vector system for the production of a polypeptide having the biological activity of KGA channel which comprises the above vector in a suitable host. This invention also provides a method for isolating from a sample a nucleic acid molecule encoding an inward rectifier, G-protein activated, potassium channel in a sample which comprises: (a) isolating the nucleic acids from the sample; (b) contacting the isolated nucleic acids with the molecule of at least 15 nucleotides capable of specifically hybridizing with the above nucleic acid molecule which encode inward rectifier, G-protein activated, mammalian, potassium KGA channel under the conditions permitting complex formation between the nucleic acid molecule encoding an inward rectifier, G-protein activated, potassium channel and the nucleic acid molecule of at least 15 nucleotides capable of specifically hybridizing with the above nucleic acid molecule which encode inward rectifier, G-protein activated, mammalian, potassium KGA channel; (c) isolating the complex formed; and (d) separating the nucleic acid molecule encoding an inward rectifier, G-protein activated, potassium channel from the complex, thereby isolating the nucleic acid molecule encoding an inward rectifier, G-protein activated, potassium channel.

DNA encoding inward rectifier, G-protein activated, mammalian, potassium KGA channel and uses thereof

The invention provides antibodies directed against a G protein-activated, inward rectifying KGA potassium channel polypeptide.

Antibodies to a G protein-activated, inward rectifying KGA potassium channel

Nucleic acids encoding mammalian 'KGA' potassium channels are provided. Vectors and transformed host cells are also provided. The KGA channels exhibit inward rectification and are activated by a G-protein. The products of the invention are useful in screening assays to identify modulators of the KGA channel and in methods for identifying or preparing nucleic acids encoding the KGA channel or related potassium channels.

DNA encoding inward rectifier, G-protein activated, mammalian, potassium

Compositions and methods are provided for producing functional mammalian inward rectifier, G-protein activated potassium channels (Kir3.0 channels). A channel is a multimeric protein comprising one or more Kir3.0 polypeptides, e.g. Kir3.1, Kir3.2, etc., where the polypeptides may be from the same or different species. The functional channel has the distinctive features of an anomalous rectifier, in that it conducts inward but not outward K.sup.+ current; it is blocked by low concentrations of extracellular Cs.sup.+ or Ba.sup.2+ ; and the conductance of the channel does not depend solely on voltage, but on (E--E.sub.K). The ability of the channel to conduct inward K.sup.+ current is modulated by G-proteins, particularly G-proteins of the G.sub.i /G.sub.o family. A number of mammalian cell surface receptors activate G-proteins as a consequence of specific ligand binding. The signal transduction from receptor to Kir3.0 channel is therefore coupled through G-protein intermediates. The functional Kir3.0 channels are useful in drug screening assays directed to modulation of cellular electrophysiology. Nucleic acids encoding Kir3.0 polypeptides are useful for expression of the gene product, and for identification of homologous genes from other species, as well as other members of the same family of proteins. Expression of the nucleic acids in a heterologous cell, e.g. Xenopus oocyte, confers the ability to cause a change in potassium flow in response to G-protein activation.

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Sierra Madre, CA, United States of America

Norman Davidson