Phosphoinositide-specific phospholipase C (PLC) isozymes play a critical role in cellular signaling by hydrolyzing phosphatidylinositol 4,5-bisphosphate (PIP2), generating intracellular messengers diacylglycerol and inositol 1,4,5-trisphosphate, which activate protein kinase C and intracellular Ca²+ release. PIP2 also modulates various cellular processes, including actin polymerization and signaling protein interactions. PLC isozymes are divided into three types: β, γ, and δ, with distinct structural and functional characteristics. The PLC-β isozymes contain a PH domain and SH domains, while PLC-γ isozymes have an additional PH domain and SH2 and SH3 domains. The PLC-δ isozymes are smaller and contain a PH domain, EF-hand, and C2 domain. The structure of PLC-δ1 suggests a catalytic mechanism involving tethering and fixation, with calcium playing a key role in C2 domain function. PLC-β is activated by G-proteins, particularly Gqα subunits, and Gβγ subunits. The activation of PLC-β is regulated by various receptors, including those for thromboxane A2, bradykinin, and angiotensin II. PLC-γ is activated by protein tyrosine kinases, such as those involved in growth factor signaling. Tyrosine phosphorylation of PLC-γ is essential for its activation, and mutations in these sites can impair signaling. PLC-γ is also activated by lipid-derived second messengers, such as phosphatidic acid and PIP3, generated by PLD and PI3-kinase, respectively. PLC-δ is activated by G-proteins and other signaling molecules, and its activity is influenced by calcium levels. PLC signaling also occurs in the nucleus, with PLC-β1 being the major isoform detected there. The amount of nuclear PLC-β1 correlates with PIP2 hydrolysis and is essential for DNA synthesis in response to growth factors. PLC activity can be inhibited by protein kinases A and C, which phosphorylate PLC and modulate its function. Genetic studies have shown that mutations in PLC genes can lead to various diseases, including postnatal dwarfism and bleeding disorders. The regulation of PLC isozymes is complex, involving multiple signaling pathways and interactions with various cellular components. Understanding the regulation of PLC isozymes is essential for elucidating the mechanisms of cellular signaling and disease.Phosphoinositide-specific phospholipase C (PLC) isozymes play a critical role in cellular signaling by hydrolyzing phosphatidylinositol 4,5-bisphosphate (PIP2), generating intracellular messengers diacylglycerol and inositol 1,4,5-trisphosphate, which activate protein kinase C and intracellular Ca²+ release. PIP2 also modulates various cellular processes, including actin polymerization and signaling protein interactions. PLC isozymes are divided into three types: β, γ, and δ, with distinct structural and functional characteristics. The PLC-β isozymes contain a PH domain and SH domains, while PLC-γ isozymes have an additional PH domain and SH2 and SH3 domains. The PLC-δ isozymes are smaller and contain a PH domain, EF-hand, and C2 domain. The structure of PLC-δ1 suggests a catalytic mechanism involving tethering and fixation, with calcium playing a key role in C2 domain function. PLC-β is activated by G-proteins, particularly Gqα subunits, and Gβγ subunits. The activation of PLC-β is regulated by various receptors, including those for thromboxane A2, bradykinin, and angiotensin II. PLC-γ is activated by protein tyrosine kinases, such as those involved in growth factor signaling. Tyrosine phosphorylation of PLC-γ is essential for its activation, and mutations in these sites can impair signaling. PLC-γ is also activated by lipid-derived second messengers, such as phosphatidic acid and PIP3, generated by PLD and PI3-kinase, respectively. PLC-δ is activated by G-proteins and other signaling molecules, and its activity is influenced by calcium levels. PLC signaling also occurs in the nucleus, with PLC-β1 being the major isoform detected there. The amount of nuclear PLC-β1 correlates with PIP2 hydrolysis and is essential for DNA synthesis in response to growth factors. PLC activity can be inhibited by protein kinases A and C, which phosphorylate PLC and modulate its function. Genetic studies have shown that mutations in PLC genes can lead to various diseases, including postnatal dwarfism and bleeding disorders. The regulation of PLC isozymes is complex, involving multiple signaling pathways and interactions with various cellular components. Understanding the regulation of PLC isozymes is essential for elucidating the mechanisms of cellular signaling and disease.