title: Lysine200 located in the fifth transmembrane domain of the histamine H1 receptor interacts with histamine but not with all H1 agonists.
abstract: Previously, we have shown that asparagine207 in the fifth transmembrane domain of the histamine H1 receptor is crucial for the binding of the N tau-nitrogen of the imidazole ring of histamine (Leurs et al., Biochem. Biophys. Res. Commun., 201, 295, 1994). In view of the potential interaction of the imidazole ring of histamine with a binding site, formed by asparagine207 and lysine200, we mutated lysine200 in the fifth transmembrane domain of the histamine H1 receptor to a non-functional alanine residue. This mutation did not affect the binding of the tested H1 receptor antagonists but resulted in a 5-fold lower affinity for histamine. The binding of other H1 receptor agonists was not affected. In stably transfected CHO cells histamine was 55-fold less effective in activating the H1Lys200Ala receptor (EC50 = 66 microM) compared to the wild type H1 receptor (EC50 = 1.2 microM). Receptor activation by the 2-methyl and the 2-(3-bromophenyl)-analogues however was hardly affected by the mutation, indicating that the 2-substituent probably prevents the interaction with the lysine200 residue. Finally, the Lys200Ala mutation reduced the production of [3H]inositol phosphates, stimulated by the non-imidazole H1 receptor agonist 2-pyridylethylamine. These data indicate that lysine200 interacts with the N pi-nitrogen of histamine and is important for the activation of the H1 receptor by histamine and the non-imidazole agonist 2-pyridylethylamine.
authors.affiliation: Leiden/Amsterdam Center for Drug Research, Department of Pharmacochemistry, Vrije Universiteit, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Leurs
authors.forename: M J
authors.initials: MJ
authors.lastname: Smit
authors.forename: R
authors.initials: R
authors.lastname: Meeder
authors.forename: A M
authors.initials: AM
authors.lastname: Ter Laak
authors.forename: H
authors.initials: H
authors.lastname: Timmerman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D017931:DNA Primers; D006168:Guinea Pigs; D006632:Histamine / Q000737:chemistry*; D017442:Histamine Agonists / Q000737:chemistry*; D006801:Humans; D008239:Lysine / Q000737:chemistry*; D008969:Molecular Sequence Data; D011969:Receptors, Histamine H1 / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D017442:Histamine Agonists; D011969:Receptors, Histamine H1; D006632:Histamine; D008239:Lysine