Characterization of specific binding sites for [3H]2-MeS-ADP on megakaryocytoblastic cell lines in culture.
Binding of [3H]2-methyl thio-adenosine 5' diphosphate ([3H]2-MeS-ADP), a stable analogue of adenosine 5' diphosphate (ADP) to DAMI and Meg-01, two megakaryocytoblastic cell lines, was time-dependent, reversible and saturable. Scatchard analysis of the saturation binding data indicated that [3H]2-MeS-ADP bound to one class of specific binding sites with high affinity (dissociation constants = 45.3 +/- 13.4 and 48.2 +/- 17.7 nM, and maximum binding capacities = 341.2 +/- 31.1 and 903 +/- 98 fmole/10(6) cells for DAMI and Meg-01, respectively) (N = 3). Unlabelled 2-MeS-ADP competitively and selectively inhibited the specific binding of [3H]2-MeS-ADP on DAMI and Meg-01 with inhibitory constant values of 118 +/- 11 and 38 +/- 11 nM, respectively (N = 3). ADP was 3 to 10 times less potent than 2-Mes-ADP in displacing [3H]2-MeS-ADP from its binding sites on DAMI and Meg-01, whereas other ADP analogues, such as AMP, GDP, UDP, adenosine or FSBA, did not interfere with the binding of [3H]2-MeS-ADP, suggesting that DAMI and Meg-01 contain ADP-specific receptors.
Savi
P
P
Haemobiology Research Department, Sanofi Recherche, Toulouse, France.
Troussard
A
A
Herbert
J M
JM
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D001665:Binding Sites; D002478:Cells, Cultured; D008533:Megakaryocytes / Q000378:metabolism*; D013873:Thionucleotides / Q000378:metabolism*; D014316:Tritium
D013873:Thionucleotides; D014316:Tritium; C002480:methylthio-ADP; D000244:Adenosine Diphosphate