Contribution of conserved glycine residues to ATP action at human P2X 1 receptors: Mutagenesis indicates that the glycine at position 250 is important for channel function

Helen R. Digby, Jonathan A. Roberts, Michael J. Sutcliffe, Richard J. Evans

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Glycine residues can introduce flexibility in proteins, give rise to turns and breaks in secondary structure and are key components of some nucleotide binding motifs. In the P2X receptor extracellular ATP binding domain, 11 glycine residues are completely conserved and an additional five are conserved in at least five of the seven family members. We have mutated individual conserved glycine residues and determined their effect on the ATP sensitivity and time-course of P2X1 receptors expressed in Xenopus oocytes. In the majority of cases, replacement by alanine had no or a less than 3-fold effect on ATP sensitivity and time-course of responses. G71A resulted in a 6-fold decrease in ATP potency and ATP (10 mM) failed to evoke functional responses from G96A, G250A and G301A mutant receptors. However, proline or cysteine could substitute for glycine at positions 96 and 301, giving receptors that were essentially normal. At glycine 250 substitution by serine gave functional responses to ATP with no effect on ATP sensitivity but a reduction in peak amplitude; in contrast, functional responses were not recorded when glycine 250 was replaced by the amino acids alanine, cysteine, aspartate, phenylalanine, isoleucine, lysine, proline or asparagine. These results suggest that glycine 250 plays an important role in determining the function of P2X receptors. © 2005 International Society for Neurochemistry.
    Original languageEnglish
    Pages (from-to)1746-1754
    Number of pages8
    JournalJournal of neurochemistry
    Volume95
    Issue number6
    DOIs
    Publication statusPublished - Dec 2005

    Keywords

    • ATP
    • Glycine
    • Mutagenesis
    • P2X receptor

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