Phospholipase C δ-type consists of three isozymes: bovine PLCδ2 is a homologue of human/mouse PLCδ4

To date, 12 phospholipase C (PLC) isozymes have been identified in mammals, and they are divided into five classes, β-, γ-, δ-, #x03B5;-, and ζ-type. PLCδ-type is reported to be composed of four isozymes, PLCδ1–δ4. Here we report that a screening for mouse PLC<f>δ</f>2 from a BAC library with primers that amplify a specific region of bovine PLCδ2 resulted in isolation of one clone containing the mouse PLC<f>δ</f>4 gene. Furthermore, a database search revealed that there is only one gene corresponding to PLC<f>δ</f>2 and PLC<f>δ</f>4 in the mouse and human genomes, indicating that bovine PLC<f>δ</f>2 is a homologue of human and mouse PLC<f>δ</f>4. However, PLCδ2 Western blot analysis with a widely used commercial anti-PLCδ2 antibody showed an expression pattern distinct from that of PLCδ4 in wild-type mice. In addition, an 80-kDa band, which was recognized by antibody against PLCδ2, was smaller than an 85-kDa band detected by anti-PLCδ4 antibody, and the 80-kDa band was detectable in lysates of brain, testis, and spleen from PLCδ4-deficient mice. We also found that immunoprecipitates from brain lysates with this PLCδ2 antibody contained no PLC activity. From these data, we conclude that bovine PLCδ2 is a homologue of human and mouse PLCδ4, and that three isozymes (δ1, δ3, and δ4) exist in the PLCδ family. [Copyright &y& Elsevier]