May 16, 2019

Johns Hopkins Medicine scientists say that new experiments with mouse eye tissues strongly suggest that a longstanding “textbook concept” about the way a mammal’s retina processes light needs a rewrite.

The enduring concept took root more than 30 years ago when researchers doing experiments in frog retinas found that when a single particle of light, known as a photon, is absorbed by light-sensing cells called rods, it starts a cascade of biochemical reactions that involve around 500 molecules called G proteins.

Now, Johns Hopkins vision scientists say that their experiments show that the number of G protein molecules activated in the cascade of reactions is far fewer — involving only 10–20 of them in the rods of mice.