phototransduction

Definition

Target type: biologicalprocess

The sequence of reactions within a cell required to convert absorbed photons into a molecular signal. [GOC:go_curators]

Phototransduction is the process by which light is converted into an electrical signal in the retina. It begins with the absorption of light by photoreceptor cells, specifically rod and cone cells. These cells contain light-sensitive pigments, rhodopsin in rods and photopsin in cones. When light strikes rhodopsin, it undergoes a conformational change, activating a protein called transducin. Transducin, in turn, activates phosphodiesterase, an enzyme that breaks down cyclic GMP (cGMP). cGMP is normally bound to sodium channels in the plasma membrane of the photoreceptor cell, keeping them open and allowing sodium ions to flow into the cell. When cGMP is broken down, the sodium channels close, reducing the flow of sodium ions and hyperpolarizing the cell. This change in membrane potential is the electrical signal that is transmitted to other neurons in the retina, eventually leading to the perception of light.'
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Proteins (3)

Compounds (7)