Summary
Human melanopsin peaks at 479 nm and couples to both Gq and Gi/o G-protein pathways, confirming its role in calcium and cAMP signaling cascades relevant to circadian entrainment. These findings validate the use of rodent models for developing light-based or pharmacological interventions targeting the melanopsin system.
Key Findings
- Human melanopsin action spectrum peaks at 479 nm, consistent with an opsin:vitamin A1 pigment template.
- Light stimulation of human melanopsin produces a high-amplitude increase in intracellular calcium and a modest reduction in cAMP, indicating coupling to both Gq and Gi/o G-protein classes.
- Chicken Opn4m and Opn4x showed additional Gs activity alongside strong Gq/11 responses, indicating species-specific differences in G-protein coupling.
- Human and mouse melanopsin share similar G-protein selectivity and spectral sensitivity profiles, supporting rodent models as valid proxies for human melanopsin research.
Categories
The Science of Light: Directly characterizes human melanopsin's spectral sensitivity (peak 479 nm) and G-protein coupling mechanisms, foundational for understanding ipRGC-driven non-visual light responses.
Author(s)
RCP Borges
Publication Year
2013
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