title: A histidine scan to probe the flexibility of the rat P2X2 receptor zinc-binding site.
abstract: The response of P2X(2) receptors to submaximal concentrations of ATP is potentiated by low levels of extracellular zinc. Histidines 120 and 213 have previously been shown to be essential in binding zinc across an intersubunit binding site. We tested the flexibility of the zinc-binding site by making mutations that had the effect of shifting the two essential histidines up to 13 residues upstream or downstream from their original positions and then testing the ability of the mutated receptors to respond to zinc. Using this method, we were able to explore potential orientations of the two regions relative to one another. Our data are consistent with a moderately flexible zinc-binding site and inconsistent with parallel and anti-parallel orientations of the regions surrounding histidines 120 and 213.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, USA.
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Tittle
authors.forename: Jamila M
authors.initials: JM
authors.lastname: Power
authors.forename: Richard I
authors.initials: RI
authors.lastname: Hume
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D006639:Histidine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D058476:Receptors, Purinergic P2X2; D014982:Xenopus laevis; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
chemical_list: C546403:P2rx2 protein, rat; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D006639:Histidine; D000255:Adenosine Triphosphate; D015032:Zinc