Inhibitory effects of ATP and other nucleotides on atrial natriuretic peptide (ANP) binding to R1-type ANP receptors in human neuroblastoma NB-OK-1 cell membranes.
ATP dose-dependently inhibited rat 125I-ANP-(99-126) binding to membranes from the human neuroblastoma cell line NB-OK-1 by increasing the KD value for the hormone without altering the Bmax value. After a 20 min preincubation with 37.5 pM 125I-ANP-(99-126) and 0.5 mM ATP, followed by the addition of 0.3 microM unlabelled ANP-(99-126), the proportion of rapidly dissociating receptors was 4-times higher than in the absence of ATP. The other nucleotides ADP, AMP, AMP-PNP, ATP gamma S, GTP, GDP, GMP, GMP-PNP and GTP gamma S were also inhibitory but with a lower potency and/or efficacy. Binding equilibrium data were satisfactorily simulated by a computer program based on partially competitive binding of ANP-(99-126) and the nucleotides, and this, together with the data on dissociation kinetics, strongly suggests that several nucleotides, when added at concentrations up to 1 mM, form a ternary ANP-receptor-nucleotide complex.
Delporte
C
C
Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium.
Winand
J
J
Poloczek
P
P
Brunko
E
E
Tastenoy
M
M
Waelbroeck
M
M
Christophe
J
J
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009447:Neuroblastoma / Q000378:metabolism*; D009711:Nucleotides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000378:metabolism*; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D009711:Nucleotides; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D000249:Adenosine Monophosphate; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate; D017461:Receptors, Atrial Natriuretic Factor