mGluR6 2026-11-05
mGluR6 is metabotropic glutamate receptor subtype 6, a receptor protein involved in transmission from photoreceptors to ON retinal bipolar cells. Reduced glutamate release in light is coupled through mGluR6 to a depolarizing response. The receptor and the downstream TRPM1 channel are distinct components.[ref]
TRPM1 is required for the depolarizing light response in retinal ON-bipolar cells by Catherine W. Morgans and others. Abstract: receptor-controlled depolarizing current
A 1995 gene knockout experiment tested that role directly. Mice lacking mGluR6 lost the measured ON responses while retaining OFF responses to light. Gross retinal organization and projections showed no obvious changes; light-conditioned avoidance behaviour remained.[ref]
The preserved OFF response is an illuminating internal comparison: failure of one transmission route does not establish failure of all visual signalling. Likewise, detecting an intact layer of neurons does not establish that its molecular signalling machinery works. The 2009 TRPM1 experiments later helped distinguish the receptor stage from the channel that carries the depolarizing current.[ref]
TRPM1 is required for the depolarizing light response in retinal ON-bipolar cells by Catherine W. Morgans and others. Figures 3–4: electroretinography and bipolar-cell recordings
M. Masu 2026-11-05
M. Masu is the first author of a 1995 experiment testing the role of mGluR6 in retinal signalling. The team generated mice lacking this glutamate receptor and compared responses to the onset and offset of light.[ref]
The gene knockout removed the measured ON response while leaving the OFF response intact. Gross retinal organization and optic projections showed no obvious changes, and light-conditioned avoidance behaviour remained.[ref]
Specific deficit of the ON response in visual transmission by targeted disruption of the mGluR6 gene by M. Masu and others. Abstract: electrophysiological, anatomical and behavioural comparisons
These comparisons distinguish failure of a specific signalling route from total loss of vision. A preserved-looking layer of neurons need not transmit signals normally; conversely, a defect in ON retinal bipolar cells need not eliminate information carried by the OFF pathway. The initial-only byline is retained without inferring additional biographical details.