Phospholipase C delta-type consists of three isozymes: bovine PLC delta 2 is a homologue of human/mouse PLC delta 4

To date, 12 phospholipase C (PLC) isozymes have been identified in mammals, and they are divided into five classes, ??-, ??-, ??-, ??-, and ??-type. PLC??-type is reported to be composed of four isozymes, PLC??1-??4. Here we report that a screening for mouse PLC??2 from a BAC library with primers that amplify a specific region of bovine PLC??2 resulted in isolation of one clone containing the mouse PLC??4 gene. Furthermore, a database search revealed that there is only one gene corresponding to PLC??2 and PLC??4 in the mouse and human genomes, indicating that bovine PLC??2 is a homologue of human and mouse PLC??4. However, PLC??2 Western blot analysis with a widely used commercial anti-PLC??2 antibody showed an expression pattern distinct from that of PLC??4 in wild-type mice. In addition, an 80-kDa band, which was recognized by antibody against PLC??2, was smaller than an 85-kDa band detected by anti-PLC??4 antibody, and the 80-kDa band was detectable in lysates of brain, testis, and spleen from PLC??4-deficient mice. We also found that immunoprecipitates from brain lysates with this PLC??2 antibody contained no PLC activity. From these data, we conclude that bovine PLC??2 is a homologue of human and mouse PLC??4, and that three isozymes (??1, ??3, and ??4) exist in the PLC?? family.close322