[What do we know about the molecular mechanism of visual excitation?].
The mechanism of transduction of the light stimulus into an electrical response signal is described for visual cells of vertebrates and invertebrates. Absorption of a photon by a rhodopsin molecule in the photosensory membrane of the visual cell leads to a delayed, relatively large single-photon-evoked response, the elementary excitatory response. The rhodopsin molecule starts an enzyme cascade via a G-protein. This leads to a considerably amplified decrease (vertebrates), or increase (invertebrates) of a large number of intracellular messenger molecules. Binding of these messenger molecules causes the opening of the sodium-preferring ion channels in the plasma membrane. Our present knowledge of the molecular mechanisms involved is described.
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Biologie II der Rheinisch-Westfälischen Technischen Hochschule, Aachen.
D000818:Animals; D007448:Invertebrates / Q000502:physiology; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*; D012243:Rhodopsin / Q000502:physiology; D014714:Vertebrates / Q000502:physiology; D014785:Vision, Ocular; D014796:Visual Perception
D012243:Rhodopsin
Was wissen wir über den molekularen Mechanismus der Erregung von Lichtsinneszellen?