Identification of group X secretory phospholipase A2 as a natural ligand for mouse phospholipase A2 receptor

Phospholipase A(2) receptor (PLA(2)R) mediates various biological responses elicited by group IB secretory phospholipase A(2) (sPLA(2)-IB). The recently cloned group X sPLA(2) (sPLA(2)-X) possesses several structural features characteristic of sPLA(2)-IB. Here, we detected a specific binding site of sPLA(2)-X in mouse osteoblastic MC3T3-E-1 cells. Cross-linking experiments demonstrated its molecular weight (180 kDa) to be similar to that of PLA(2)R, In fact, sPLA(2)-X was found to bind the recombinant PLA(2)R expressed in COS-7 cells, and its specific binding detected in mouse lung membranes was abolished by the deficiency of PLA(2)R. These findings demonstrate sPLA(2)-X to be one of the high-affinity ligands for mouse PLA(2)R, (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.