The latest phospholipase C, PLCη, is implicated in neuronal function

Members of the phosphoinositide-specific phospholipase C (PLC) family have key roles in cell signalling. In response to many extracellular stimuli, such as hormones, neurotransmitters, antigens and growth factors, PLCs catalyse the hydrolysis of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P-2], thereby generating two well-established second messengers, inositol (1,4,5)-trisphosphate and diacylglycerol. Eleven PLC isozymes encoded by different genes have been identified in mammals and, on the basis of their structure and sequence relationships, have been classified into five families designated PLC beta (1-4), PLC gamma (11 and 2), PLC delta (1, 3 and 4), PLC epsilon (1) and PLC zeta (1). All PLCs contain the catalytic X and Y domain, in addition to other regulatory domains including the C2 domain and the EF-hand domain. In 2005, four groups independently identified an entirely new family of PLCs - eta 1 and eta 2 - using data mining of mammalian genomes. The properties of the PLC eta enzyme suggest that it might act as a Ca2+ sensor, in particular, functioning during formation and maintenance of the neuronal network in the postnatal brain.