Phosphoinositide-specific phospholipase C (PLC) is a crucial enzyme in transmembrane signaling. A cDNA encoding the putative phospholipase C was cloned from human lymphocytes that were transformed by infection with Epstein-Barr virus. The deduced amino acid sequence of the cDNA accounted for 146.1 kDa of the molecular mass of the complete enzyme and showed 50.2% sequence similarity to bovine brain PLC. This cDNA contained regions, the sequences of which were similar to those of some tyrosine kinase-related oncogene products. Northern blotting demonstrated that the mRNA for this PLC is expressed in human promyelocytic leukemia cells (HL-60). Since the other cloned cDNAs for PLCs could not hybridize with the RNA from this cell, it is strongly suggested that the gene obtained here encodes an additional isozyme of PLC in blood cells.
