Inhibition of an inwardly rectifying K+ channel by G-protein alpha-subunits

Article Abstract:

The G-alpha subunits of heterotrimeric G proteins suppress the activity of K+ channels of the GIRK family. Free GTP-gamma-S-activated G(sub alpha-i1) subunit suppress the GIRK activity induced by G(sub beta-1-gamma-2) in the membranes of Xenopus oocytes expressing GIRK1. G(sub alpha-i2) and G(sub alpha-i3) have no effect on GIRK in Xenopus. G(sub alpha-s)-GTP-gamma-S inhibits GIRK activity partially. The coupling of G proteins to GIRKs appears to be regulated by antagonistic interactions between G(sub alpha) and G(sub beta-gamma) proteins.

G proteins

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Promiscuous coupling between the sulphonylurea receptor and inwardly rectifying potassium channels

Article Abstract:

Coupling between the sulphonylurea receptor (SUR) and various potassium channels induces sulphonylurea sensitivity in inwardly-rectifying K-channels. Intrinsic channel activity is absent in the SUR of Xenopus oocyte and unable to induce ATP-sensitivity in endogenous potassium channels of HEK293 cells. The expression of SUR in HEK293 enhances the binding of (3H)glibenclamide. SUR regulates beta cell K-ATP channel activity and induces ATP-sensitivity in beta-cell K-ATP channels through nucleotide-binding.

Research, Adenosine triphosphate, ATP, Drug receptors

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Cloning and expression of an inwardly rectifying ATP-regulated potassium channel

Article Abstract:

ROMK1 is a potassium (K+) ion channel polypeptide protein whose amino acid sequence and unusual structure have been inferred from the cloning of complementary DNA from mammalian kidney. ROMK1 conserves an amino acid sequence homologous to the H5 region of the voltage-gated K+ channel. Moreover, ROMK1 consists of two potential cell membrane-spanning helices and an adenosine triphosphate-binding domain.

Genetic aspects, Polypeptides, Adenosine triphosphatase

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