A rhodopsin molecule (yellow) with bound retinal (orange), embedded in a cell membrane (lipids shown as green, head groups as red/blue).

Bovine rhodopsin

Rhodopsin, also known as visual purple, is expressed in vertebrate photoreceptor cells. It is a pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light. Rhodopsins belong to the class of G-protein coupled receptors. It is the chemical that allows night-vision, and is extremely sensitive to light. Exposed to white light, the pigment immediately bleaches, and it takes about 30 minutes to regenerate fully in humans. Image File history File links This work is copyrighted. ... Image File history File links Bovine_rhodopsin. ... Image File history File links Bovine_rhodopsin. ... Hugo is a masculine name. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The National Center for Biotechnology Information (NCBI) is part of the US National Library of Medicine (NLM), which is a branch of the US National Institutes of Health. ... Swiss-Prot is a curated biological database of protein sequences created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute. ... In biology and evolutionary computation, a locus is the position of a gene (or other significant sequence) on a chromosome. ... Chromosome 3 is one of the 23 pairs of chromosomes in humans. ... Classes and Clades See below Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... A photoreceptor is a specialized form of cell (specifically, neuron) that is capable of phototransduction. ... For animal and plant pigments, see Pigment, biology. ... Human eye cross-sectional view. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength [citation needed]. The elementary particle that defines light is the photon. ... In cell biology, G-protein-coupled receptors, also known as GPCR, seven transmembrane receptors, heptahelical receptors, or 7TM receptors, are a class of transmembrane receptors. ...

Rhodopsin consists of two building blocks, an opsin protein called scotopsin and a reversibly covalently bound cofactor, retinal (retinaldehyde). The structure of rhodopsin consists of a bundle of seven transmembrane helices that surround the photoreactive chromophore, 11-cis retinal. Retinal, the chromophore portion of rhodopsin, is made in the retina from Vitamin A. Isomerization of 11-cis-retinal into all-trans-retinal by light induces a conformational change in the opsin that activates the associated G protein and triggers a second messenger cascade. A rhodopsin molecule in the cell membrane. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ... A cofactor is the following: In mathematics a cofactor is the minor of an element of a square matrix. ... In the vision system, retinal, technically called retinene1 or retinaldehyde, is a light-sensitive retinene molecule found in the photoreceptor cells of the retina. ... Chromophore is a term that describes the moiety of a molecule responsible for its color. ... Human eye cross-sectional view. ... Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. ... In chemistry, isomerization is the transformation of a molecule into a different isomer. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength [citation needed]. The elementary particle that defines light is the photon. ... G-proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. ... In biology, second messengers are low-weight diffusible molecules that are used in signal transduction to relay signals within a cell. ...

Rhodopsin of the rods most strongly absorbs green-blue light and therefore appears reddish-purple, which is why it is also called "visual purple". It is responsible for the monochromatic vision in the dark. Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ...

Several closely related opsins, the photopsins, exist that differ only in a few amino acids and in the wavelengths of light that they absorb most strongly. These pigments are found in the different types of the cone cells of the retina and are the basis of color vision. Humans have three different other opsins beside rhodopsin, with absorption maxima for yellowish-green (photopsin I), green (photopsin II), and bluish-violet (photopsin III) light. Normalised absorption spectra of the three human photopsins and of human rhodopsin (dashed). ... The general structure of an amino acid molecule, with the amine group on the left and the carboxyl group on the right. ... The wavelength is the distance between repeating units of a wave pattern. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ... Color vision is the capacity of an organism or machine to distinguish objects based on the wavelength of the light they reflect or emit. ...

Some archaea express a proton pump called bacteriorhodopsin to carry out photosynthesis. Like rhodopsin, bacteriorhodopsin contains retinal and has seven transmembrane alpha helices; however it is not coupled to a G protein. An alga is known to have an opsin that contains its own monolithic light-gated ion channel, channelrhodopsin-2. Phyla / Classes Phylum Crenarchaeota Phylum Euryarchaeota     Halobacteria     Methanobacteria     Methanococci     Methanopyri     Archaeoglobi     Thermoplasmata     Thermococci Phylum Korarchaeota Phylum Nanoarchaeota Archaea (; from Greek αρχαία, old ones; singular Archaeum, Archaean, or Archaeon), also called Archaebacteria (), is a major division of living organisms. ... A proton pump is an integral membrane protein that is capable of moving protons across the membrane of a cell, mitochondrion, or other subcellular compartment, thereby creating a difference or gradient in both pH and electrical charge (ignoring differences in buffer capacity) and tending to establish an electrochemical potential. ... Bold textLink titleLink title Bacteriorhodopsin is the photosynthetic pigment used by archaea, most notably halobacteria. ... The leaf is the primary site of photosynthesis in plants. ... Within an integral membrane protein, a transmembrane helix is a segment that is alpha-helical in structure, roughly 20 amino acids in length and (though it may be presumed to lie within the protein, out of contact with the surrounding lipid bilayer) is said to span the membrane. ... Channelrhodopsins are ion channels that are directly opened by light. ...

Normalised absorption spectra of human rhodopsin (dashed) and the three photopsins.

Spectral absorption curves of the short (S), medium (M) and long (L) wavelength pigments in human cone and rod (R) cells. ... Spectral absorption curves of the short (S), medium (M) and long (L) wavelength pigments in human cone and rod (R) cells. ...

External links

• Photoisomerization of rhodopsin, Excellent animation.
• Rhodopsin and the eye, an excellent summary with pictures.
• Rhodopsin - Light Receptor