A UC Irvine team led by physiology & biophysics professor Todd C. Holmes has discovered a second form of phototransduction light sensing in cells – this one derived from vitamin B2. Phototransduction is the conversion of light signals into electrical signals in photoreceptive cells. For more than a century, it was believed that the process was solely based on a chemical, retinal, derived from vitamin A. Holmes’ team found that phototransduction can also be mediated by a protein called cryptochrome, which uses a vitamin B2 chemical derivative for light sensing. “This discovery opens new opportunities for adapting light-sensing proteins to drive medically relevant cellular activities,” Holmes said. The study appears online in Science.