Protein kinase C (PKC) is a family of serine- and threonine-specific protein kinases that can be activated by calcium and the second messenger diacylglycerol. Novel (n)PKCs include the δ, ε, η, and θ isoforms, and require DAG, but do not require Ca2+ for activation. Thus, conventional and novel PKCs are activated through the same signal transduction pathway as phospholipase C. On the other hand, atypical (a)PKCs (including protein kinase Mζ and ι / λ isoforms) require neither Ca2+ nor diacylglycerol for activation.
