Some properties of a purinergic receptor solubilized from human uterus membranes

Abstract

A purinergic receptor was identified in human myometrium membranes using 5'-N-[3H]ethylcarboxamide-adenosine [( 3H] NECA) as radioligand. Scatchard analysis of the binding data gave a Kd of 123 nM with 2.3 pmol ligand bound/mg protein. Displacement studies indicated that the binding site had the characteristics of the A2 adenosine receptors and some of those of the P2 purinoceptors since it was inhibited by two slowly degradable ATP derivatives with IC50 values comparable to that of NECA. The receptor was solubilized with sodium cholate and its binding properties were the same as those of the membrane-bound form. No -SH group appeared to be essential for the binding activity. By density gradient centrifugation the purinergic receptor-detergent complex was estimated to have an apparent molecular mass of 95 kDa.