SPECIFIC BINDING-SITES FOR PROSTAGLANDIN-D2 ON HUMAN-PLATELETS

3H-PGD2 was biosynthesized from 3H-arachidonate and used to study the binding of PGD2 to intact human platelets. The binding of 3H-PGD2 to platelets was rapid, being essentially complete within two min. Bound 3H-PGD2 PGD2. Scatchard analysis of concentration-dependent binding indicated a single class of binding sites with a dissociation constant (KD) of 4.12 × 10-7M and a capacity of 760 sites per platelet. The relative ability of PGD2, PGE2, PGE1 and PGI2 to displace 3H-PGD2 bound to these sites was 100:2:2<1. We conclude therefore, that these PGD2 binding sites are specific for PGD2 and independent of those previously demonstrated to recognize 3H-PGI2 and 3H-PGE1. © 1979.