each family displays similarities, as well as obvious distinctions, that contribute to unique regulatory properties within the cell. Because it is the only family found expressed in lower eukaryotic organisms such as yeast and slime molds, it is considered the prototypical PLC isoform. The other family members more than likely evolved from PLC-δ as their domain architecture and mechanism of activation were expanded. Although a full'' crystal structure has not been obtained, high-resolution X-ray crystallography has yielded the molecular structure of the N-terminal PH domain complexed with its product IP3, as well as the remainder of the enzyme with the PH domain ablated. These structures have provided researchers with the necessary information to begin speculating about other family members such as PLCβ2. Other PLC families PLC-ε (230-260kDa ) is activated by Ras and Rho GTPases. PLC-ζ (75kDa) is thought to play an important role in vertebrate fertilization by producing intracellular calcium oscillations important for the start of embryonic development. However, the mechanism of activation still remains unclear. This isoform is also capable of entering the early-formed pronucleus after fertilization, which seems to coincide with the cessation of calcium mobilization. It, like PLC-δ1 and PLC-β, possesses nuclear export and localization sequences. PLC-η has been implicated in neuronal functioning. Human proteins in this family PLCB1; PLCB2; PLCB3; PLCB4; PLCD1; PLCD3; PLCD4; PLCE1; PLCG1; PLCG2; PLCH1; PLCH2; PLCL1; PLCL2; PLCZ1 See also Clostridium perfringens alpha toxin Lipid signaling PH domain, found in some phospholipases C Phospholipase Zinc-dependent phospholipase C, a different family of phospholipase C References EC 3.1.4 Peripheral membrane proteins Enzymes of known structure Signal transduction Protein families Enzymes Calcium enzymes Hydrolases Calcium signaling Cell signaling G protein-coupled receptors Cell biology de:Phospholipase C es:Fosfolipasa C fr:Phospholipase C he:פוספוליפאז C ru:Фосфолипаза C