OLF-bPAC is an engineered light-gated cation channel with high Ca[2+] permeability. It can be used as an optogenetic tool to activate neuron activity; it is activated by blue light. OLF-bPAC is a fusion protein composed of the cyclic nucleotide-gated channel encoded by the Bos taurus CNGA2 gene (UniProtKB:Q03041), mutated to carry a T537S amino acid substitution, a plasma membrane trafficking signal (KSRITSEGEYIPLDQIDINV), the Venus fluorescent protein, the Beggiatoa BLUF domain regulated adenylyl cyclase (bPAC) and an endoplasmic reticulum export signal (FCYENEV) (FBrf0240386).