Solubilization of prostaglandin D2 binding protein from porcine temporal cortex

Prostaglandin (PG) D2 binding activity was retained at the highest level in the P2 fraction prepared from porcine temporal cortex with the use of buffer containing mannitol and quinacrine. Then, the activity in this fraction was solubilized with maximal recovery by 10 mM CHAPS. The specific PGD2 binding time-dependently increased and was saturated at around 70 nM. Scatchard plots were fitted to a straight line with a Kd value of 20 nM and Bmax of 120 fmol/mg protein. The binding sites showed high specificity for PGD2. In addition, heat and trypsin treatments remarkably decreased the binding activity. These results suggest that the specific binding protein for PGD2 can be solubilized from these membranes.