Cyclases

The cyclase enzymes, adenylyl cyclase and guanylyl cyclase, convert ATP and GTP to cAMP and cGMP respectively, plus pyrophosphate. These enzymes are important in the production of second messenger molecules and so have a vital role in signal transduction in a variety of physiological processes.

Subtype	Endogenous Activators	Endogenous Inhibitors

AC1	Ca²⁺/Calmodulin PKC-evoked phosphorylation	G_αi
AC2	G_βγ PKC-evoked phosphorylation	-
AC3	Ca²⁺/Calmodulin PKC-evoked phosphorylation	G_αi CaMKII-evoked phosphorylation
AC4	G_βγ	PKC-evoked phosphorylation
AC5	PKC-evoked phosphorylation	G_αi Ca²⁺ PKA-evoked phosphorylation
AC6	-	G_αi Ca²⁺ PKA-evoked phosphorylation PKC-evoked phosphorylation
AC7	PKC-evoked phosphorylation	-
AC8	Ca²⁺	-
AC9	-	Ca²⁺/calcineurin