title: Adenylated dinucleotide binding to the adenosine 5',5'''-P1,P4-tetraphosphate mouse heart receptor.
abstract: We have demonstrated specific adenosine 5',5'''-P1,P4-tetraphosphate (Ap4A) receptors at heart cell surfaces. Optimal Ap4A binding requires receptor activation. Other Investigators have demonstrated that Ap5A and Ap6A act as vasopressors. We now compare the binding of Ap4A, Ap5A and Ap6A on heart membranes to determine if all three ligands bind to the same receptor and their relative avidities. Anti-Ap4A receptor antibodies inhibit the binding of all three ligands. SDS-PAGE analysis of Ap4A, Ap5A and Ap6A cross-linked to membranes reveals that all three are attached to a 30 kDa peptide. The specific activity for binding to unactivated membranes is similar for all three ligands. However, after receptor activation there is a 3.4x increase in Ap4A binding and a 32.5x decrease in the KD; values remain unchanged for Ap5A and Ap6A. These data indicate that Ap4A, Ap5A and Ap6A bind to the same receptor on cardiac membranes but receptor activation enhances only Ap4A binding.
authors.affiliation: Department of Biological Sciences, Clemson University, SC 29634-1903.
authors.forename: R H
authors.initials: RH
authors.lastname: Hilderman
authors.forename: J E
authors.initials: JE
authors.lastname: Lilien
authors.forename: J K
authors.initials: JK
authors.lastname: Zimmerman
authors.forename: D H
authors.initials: DH
authors.lastname: Tate
authors.forename: M A
authors.initials: MA
authors.lastname: Dimmick
authors.forename: G B
authors.initials: GB
authors.lastname: Jones
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002462:Cell Membrane / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D009206:Myocardium / Q000378:metabolism*; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D000911:Antibodies, Monoclonal; D015226:Dinucleoside Phosphates; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; C080426:adenosine 5',5''',P1,P4-tetraphosphate receptor; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate; C011440:diadenosine triphosphate; C070070:diadenosine 5',5''''-P1,P6-hexaphosphate