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. Author manuscript; available in PMC: 2010 Jan 1.
Published in final edited form as: Trends Endocrinol Metab. 2008 Dec 4;20(1):25–33. doi: 10.1016/j.tem.2008.10.002

Figure 1.

Figure 1

PKC isozymes and domains. PKC isozymes are classified based upon their activation requirements, which are the result of differences in domains within the regulatory region. (a) The classical isozymes (α, βI, βII and γ) bind calcium at the C2 domain, increasing the affinity of the C1 domain for diacylglycerol (DAG). (b) The novel isozymes (ε, δ, η and θ) are not sensitive to calcium but can be activated by binding DAG. (c) The atypical isozymes (ζ and λ/ι) lack a C2 domain and a functional C1 domain and, therefore, are not sensitive to either calcium or DAG. The catalytic domains are highly conserved throughout all of the PKC isozymes, and individual isozymes contain pseudosubstrate (orange) domains, which in the absence of stimuli maintain the isozyme in an inactive conformation.