iChloC is an engineered light-gated anion channel with high selectivity for chloride. It can be used as an optogenetic tool to inhibit neuron activity; it is activated by blue light. iChloC is an artificial derivative of ChR2, containing amino acid substitutions E83Q, E90R, E101S, D156N and T159C relative to ChR2 (PMID:26443033). The formation of a functional channel requires the presence of a covalently linked all-trans-retinal chromophore which can be provided exogenously if necessary via the culture medium or diet (this cofactor is present endogenously in some intact vertebrate systems). For detailed kinetic and spectral properties, see PMID:26443033. For a comparison of iChloC and other neuron inhibition tools, see PMID:28772120.