Molecular cloning of pancreatic group I phospholipase A2 receptor

We have recently reported that mammalian pancreatic group I phospholipase A2 (PLA2-I) has its specific receptor (PLA2 receptor) on a variety of mammalian cells and that various biological responses are elicited by PLA2-I via this receptor. In this study, we cloned cDNAs encoding a protein corresponding to the bovine PLA2 receptor purified from the corpora lutea on the basis of its partial amino acid sequences. The identity of a protein encoded by the cloned cDNA with the bovine PLA2 receptor was verified by a transient expression experiment using COS-7 cells. Interestingly, the deduced primary structure of the PLA2 receptor (1,463 amino acid residues) exhibits a close relatedness throughout the molecule to that of the macrophage mannose receptor, a unique member of Ca(2+)-dependent (C-type) animal lectin family, in spite of their functional diversity. Based on this sequence similarity between these two receptors, the domain organization of the PLA2 receptor could be tentatively assigned as follows; 10 extracellular domains including 8 tandem repeats homologous to C-type carbohydrate-recognition domains (CRDs) and a single transmembrane region followed by a short cytoplasmic tail. The results of transient expression experiments for mutant PLA2 receptors supported this assignment and furthermore suggested the region responsible for PLA2-I binding corresponds to CRDs in the mannose receptor.