A light-sensitive chimeric protein includes domains from at least two members of the G-protein-coupled-receptor (GPCR) protein super family, which are fused to yield a light-sensitive GPCR chimera capable of coupling a light signal to the signaling cascade of the metabotropic glutamate receptor 6 (mGluR6) is provided for medical therapy and pharmaceuticals for treating loss of vision, in particular resulting from retinal photoreceptor degeneration. A first GPCR family member contributes domains which mediate the light-sensitivity to the chimeric light-sensitive GPCR protein and belongs to the family of light-sensitive GPCR proteins also called photopigments. In some cases, the GPCR protein is melanopsin, in particular human melanopsin. A second of the at least two GPCR family members is mGluR6, which contributes domains for coupling the light signal to the intracellular signaling cascade of mGluR6, which is a native component of the cell membrane of ON-bipolar cells in the inner retina.
