title: In human and rat lung membranes [35S]GTPgammaS binding is a tool for pharmacological characterization of G protein-coupled dinucleotide receptors.
abstract: The P2Y receptor family is activated by extracellular nucleotides such as ATP and UTP. P2Y receptors regulate physiological functions in numerous cell types. In lung, the P2Y2 receptor subtype plays a role in controlling Cl- and fluid transport. Besides ATP or UTP, also diadenosine tetraphosphate (Ap4A), a stable nucleotide, seems to be of physiological importance. In membrane preparations from human and rat lung we applied several diadenosine polyphosphates to investigate whether they act as agonists for G protein-coupled receptors. We assessed this by determining the stimulation of [35S]GTPgammaS binding. Stimulation of [35S]GTPgammaS binding to G proteins has already been successfully applied to elucidate agonist binding to various G protein-coupled receptors. Ap(n)A (n = 2 to 6) enhanced [35S]GTPgammaS binding similarly in human and rat lung membranes, an indication of the existence of G protein-coupled receptor binding sites specific for diadenosine polyphosphates. Moreover, in both human and rat lung membranes comparable pharmacological properties were found for a diadenosine polyphosphate ([3H]Ap4A) binding site. The affinity for Ap2A, Ap3A, Ap4A, Ap5A, and Ap6A was also comparable. 8-Diazido-Ap4A and ATP were less potent, whereas the pyrimidine nucleotide UTP showed hardly any affinity. Thus, we present evidence that different diadenosine polyphosphates bind to a common G protein-coupled receptor binding site in membranes derived either from human or rat lung.
authors.affiliation: Institut für Neurobiochemie, Otto-von-Guericke Universität, Magdeburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Laubinger
authors.forename: T
authors.initials: T
authors.lastname: Welte
authors.forename: G
authors.initials: G
authors.lastname: Streubel
authors.forename: H J
authors.initials: HJ
authors.lastname: Schäfer
authors.forename: G
authors.initials: G
authors.lastname: Reiser
mesh_terms: D000818:Animals; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D013045:Species Specificity; D013462:Sulfur Radioisotopes
chemical_list: D011956:Receptors, Cell Surface; D018048:Receptors, Purinergic P2; D013462:Sulfur Radioisotopes; C074644:uridine triphosphate receptors; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins