glutamate metabotropic receptor 6
The GRM6 gene provides instructions for making a protein called metabotropic glutamate receptor 6 (mGluR6). This protein is a glutamate receptor, which is a type of protein that attaches (binds) to the signaling molecule glutamate on the surface of cells. The mGluR6 protein is found within the membrane that surrounds cells called bipolar cells, which are part of the light-sensitive tissue at the back of the eye (retina). Bipolar cells receive visual signals from cells called rods that are used to see in low light. Rod cells release glutamate, which then binds to mGluR6 on bipolar cells. This binding ultimately triggers bipolar cells to transmit the visual signals to other retinal cells and eventually to the brain.
At least 25 mutations in the GRM6 gene have been found to cause autosomal recessive congenital stationary night blindness, which is characterized by the inability to see in low light and other vision problems such as nearsightedness (myopia). Most GRM6 gene mutations impair the function of the mGluR6 protein by changing single protein building blocks (amino acids) in the protein. These mutations prevent the protein from reaching the cell membrane where it is needed to bind to glutamate. Without any mGluR6 protein at the cell surface, the glutamate released from rod cells in low light is not detected by bipolar cells, so visual signals are not transmitted. The brain does not receive the visual information sent by rods, leading to difficulty seeing in low light.
- glutamate receptor, metabotropic 6
- metabotropic glutamate receptor 6
- Basic Neurochemistry (sixth edition, 1999): Metabotropic Receptors Modulate Synaptic Transmission
- Webvision: The Organization of the Retina and Visual System: Different Glutamate Receptor Types for ON and OFF Bipolar Cells
- Webvision: The Organization of the Retina and Visual System: Metabotropic Glutamate Receptors