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An atypical protein kinase C is a member of the protein kinase C family whose regulation differs from the conventional calcium- and diacylglycerol-responsive forms. Atypical isoforms participate in signalling and cellular polarity, including complexes with PAR-6. Their name describes a regulatory subfamily; it does not mean that all protein kinase C enzymes share the same activation requirements. ^[ref]

A group of interacting polarity regulators including PAR-3, PAR-6 and atypical protein kinase C. Its organization links cortical domains to junctional and morphogenetic behaviour.

Phospholipase C cleaves a phospholipid phosphodiester bond. In a prominent signalling pathway, cleavage of phosphatidylinositol 4,5-bisphosphate produces membrane-associated diacylglycerol and soluble inositol trisphosphate. The latter can stimulate calcium release from intracellular stores, while diacylglycerol regulates selected protein kinase C isoforms. The two products carry information into different cellular locations. ^[ref]

Protein kinase C is a family of protein kinases that transfers phosphate from ATP to selected serine residues or threonine residues in target proteins. Conventional members integrate calcium ion and diacylglycerol signals with membrane association, while other family members have different activation requirements. A statement about one isoform should not be assumed to describe every member. ^[ref]

A useful pathway example begins with activation of phospholipase C, which produces diacylglycerol and an inositol-phosphate signal that releases stored calcium ions. These signals can cooperate to recruit and activate a conventional protein kinase C. The downstream phosphorylation then changes target behaviour; a rise in calcium is not itself the phosphorylation reaction. ^[ref]