Hydrolysis of phosphatidylcholine with phospholipase A2 (EC 3.1.1.4) and phospholipase A1 (EC 3.1.1.32) activities. a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 2-acyl-sn-glycero-3-phosphocholine + a fatty acid + H(+) a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycero-3-phosphocholine + a fatty acid + H(+) Binds 1 Ca(2+) ion per monomer. In the dimeric form the Ca(2+) is bound by different amino acids with binding of each Ca(2+) shared with ligands coming from each monomer. The Ca(2+) ion may have a role in catalysis. Homodimer; dimerization is reversible, and the dimeric form is the active one. One of the very few enzymes located there. Belongs to the phospholipase A1 family.