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P2X receptors comprise a family of ATP-gated ion channels with the basic amino acids Lys-68, Arg-292, and Lys-309 (P2X(1) receptor numbering) contributing to agonist potency. In many ATP-binding proteins aromatic amino acids coordinate the binding of the adenine group. There are 20 conserved aromatic amino acids in the extracellular ligand binding loop of(More)
P2X receptors for ATP are expressed throughout the body and mediate a multitude of functions, including muscle contraction, neuronal excitability and bone formation. In the mid-1990s seven genes encoding P2X receptors (P2X(1-7)) were identified. These receptors comprised a novel family of ligand-gated ion channels with subunits that possessed intracellular(More)
The agonist binding site of ATP-gated P2X receptors is distinct from other ATP-binding proteins. Mutagenesis on P2X(1) receptors of conserved residues in mammalian P2X receptors has established the paradigm that three lysine residues, as well as FT and NFR motifs, play an important role in mediating ATP action. In this study we have determined whether(More)
Degenerate PCR was used to amplify DNAs encoding members of the P2Y receptor family from rat brain RNA. A full-length sequence obtained for one novel clone (R5) contained an intronless open reading frame that encoded a polypeptide of 361 amino acids, sharing 84% sequence identity with the human P2Y4 receptor. When R5 was stably expressed in Jurkat cells,(More)
P2X receptors for adenosine tri-phosphate (ATP) are a distinct family of ligand-gated cation channels with two transmembrane domains, intracellular amino and carboxy termini and a large extracellular ligand binding loop. Seven genes (P2X1-7) have been cloned and the channels form as either homo or heterotrimeric channels giving rise to a wide range of(More)
At the majority of mutants in the region Glu181-Val200 incorporating a conserved AsnPheThrPhiPhixLys motif cysteine substitution had no effect on sensitivity to ATP, partial agonists, or methanethiosulfonate (MTS) compounds. For the F185C mutant the efficacy of partial agonists was reduced by approximately 90% but there was no effect on ATP potency or the(More)
P2X receptors for extracellular ATP are a distinct family of ligand-gated cation channels involved in physiological processes ranging from synaptic transmission to muscle contraction. Common ATP binding motifs are absent from P2X receptors, and the extent of the agonist binding site is unclear. We used cysteine-scanning mutagenesis, radiolabeled 2-azido ATP(More)
The role of conserved polar glutamine, asparagine and threonine residues in the large extracellular loop, and glycosylation, to agonist action at human P2X1 receptors was tested by generating alanine substitution mutants. For the majority of mutants (Q56A, Q95A, T104A, T109A, Q112A, Q114A, T146A, N153A, T158A, N184A, N191A, N242A, N300A) alanine(More)
We have developed a novel method for quantitation of lectin binding sites in mucins derived from colon tissues. Binding of peanut agglutinin and wheat germ agglutinin was measured in extracts from normal and malignant human colon epithelium. Binding of wheat germ agglutinin was used as an estimate of the total mucin present in the tissue extract. Peanut(More)
P2X receptors for ATP have a wide range of physiological roles and comprise a structurally distinct family of ligand-gated trimeric ion channels. The crystal structure of a P2X4 receptor, in combination with mutagenesis studies, has provided a model of the intersubunit ATP-binding sites and identified an extracellular lateral portal, adjacent to the(More)