A new study has found it only takes differences in three amino acids to tune cones in the retina to be sensitive to red or green light.
The study, published in Science and led by biochemists at Nagoya Institute of Technology in Japan, could help explain why red-green colour blindness is so common, and potentially lead to new ways to treat it.1
“Colour vision allows primates to distinguish objects based on subtle differences in light wavelength,” study authors wrote.
“In humans and Old World primates, this ability depends on three types of cone cells; red, green, and blue, each using a light-sensitive pigment that is most sensitive to a different part of the visible spectrum.”
The study authors described the red- and green-sensitive pigments as “particularly intriguing” because they differ at only a few amino acid positions, “yet their light absorption peaks are separated by about 30 nanometers, enabling red-green colour discrimination”.
… this knowledge may help researchers understand how genetic variations alter colour perception
“This study reports the first three-dimensional structures of primate red- and green-sensitive cone visual pigments in their dark state,” Kota Katayama, a biochemist at Nagoya Institute of Technology, told Science Alert.2
“In the long term, this knowledge may help researchers understand how genetic variations alter colour perception and contribute to colour vision deficiencies and other visual disorders.”
References
- Ohashi S, Katayama K, Kandori H, et al. Structural insights into spectral tuning and retinal exchange in cone visual pigments. Science. 2026 Jun 25;392(6805). doi: 10.1126/science.adz3996.
- Irving M, Color blind? Just 3 amino acids separate red from green vision, Science Alert, 30 July 2026. Available at: sciencealert.com/it-takes-just-3-amino-acids-to-let-us-see-red-and-green-study-finds [accessed Aug 2026].
