OPN1SW

Blue-sensitive opsin is a protein that in humans is encoded by the OPN1SW gene. The OPN1SW gene provides instructions for making a protein that is essential for normal color vision. This protein is found in the retina, which is the light-sensitive tissue at the back of the eye.

The OPN1SW gene provides instructions for making an opsin pigment that is more sensitive to light in the blue/violet part of the visible spectrum (short-wavelength light). Cones with this pigment are called short-wavelength-sensitive or S cones. In response to light, the photopigment triggers a series of chemical reactions within an S cone. These reactions ultimately alter the cell's electrical charge, generating a signal that is transmitted to the brain. The brain combines input from all three types of cones to produce normal color vision.