Catalyzes the hydrolysis of 1-phosphatidylinositol 4,5- bisphosphate into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) and mediates intracellular signaling downstream of G protein- coupled receptors (PubMed:9188725). Regulates the function of the endothelial barrier. {ECO:0000250|UniProtKB:Q9Z1B3, ECO:0000269|PubMed:9188725}. This is the function of ENSG00000182621 (PLCB1, phospholipase C beta 1).