Photoactivated adenylyl cyclase

When illuminated with blue light, the enzyme domain becomes active and converts ATP to cAMP, an important second messenger in many cells.

In the unicellular flagellate Euglena gracilis, PACα and PACβ (euPACs) serve as a photoreceptor complex that senses light for photophobic responses and phototaxis.

[2] Small but potent PACs were identified in the genome of the bacteria Beggiatoa (bPAC) and Oscillatoria acuminata (OaPAC).

[6] PAC has been used in mice to clarify the function of neurons in the hypothalamus, which use cAMP signaling to control mating behavior.

[7] Expression of PAC together with K+-specific cyclic-nucleotide-gated ion channels (CNGs) has been used to hyperpolarize neurons at very low light levels, which prevents them from firing action potentials.

Structure of the photoactivated adenylyl cyclase OaPAC forming a homodimer. FMN: flavin mononucleotide, the light-absorbing pigment. ^{[

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