Rhodopsin synthesis

Fig. 4.18 The rhodopsin cycle. The bleaching of rhodopsin yields all-trans retinene (now more currently indicated as retinal), which must be isomerized to neoretinene b before it can regenerate the visual pigment. Alternatively, having been reduced to all trans vitamin A, the latter in turn must be isomerized to neovitamin Ab before it takes part in rhodopsin synthesis. Rod vision thus depends on the continuous stereoisomerization of all-trans retinene or vitamin A, or on the continuous replacement of these substances by new supplies of vitamin Ab from external sources (adapted from [196, 197])...

Foster, K.W., Saranak, J., and Zarrilli, G., Autoregulation of rhodopsin synthesis in Chlamydomonas reinhardtii, Proc. Natl Acad. Scl USA, 85, 6379, 1988. 

Two molecules of vitamin A are formed from one molecule of -carotene. Vitamin A crystallizes in pale yellow needles m.p. 64 C. It is optically inactive. It is unstable in solution when heated in air, but comparatively stable without aeration. Vitamin A is manufactured by extraction from fish-liver oils and by synthesis from / -ionone. The role of vitamin A in vision seems to be different from its systemic function. See also relincne and rhodopsin. 

Stammes, M.A., Shieh, B.H., Chuman, L., Harris, G.L. and Zuker, C.S. (1991) The cyclophilin homolog ninaA is a tissue-specific integral membrane protein required for the proper synthesis of a subset of Drosophila rhodopsins. Cell 65, 219-227. 

Multiple forms of heterotrimeric G proteins exist in the nervous system. Three types of heterotrimeric G protein were identified in early studies. G termed transducin, was identified as the G protein that couples rhodopsin to regulation of photoreceptor cell function (see Ch. 49), and Gs and G were identified as the G proteins that couple plasma membrane receptors to the stimulation and inhibition, respectively, of adenylyl cyclase, the enzyme that catalyzes the synthesis of cAMP (see Ch. 21). 

Rhodium compounds, 19 644-648 synthesis of, 19 646 uses for, 19 646-648 Rhodium oxide, 10 42 Rhodium plating, 9 822 19 648 Rhodium-platinum alloys, 19 602 Rhodochrosite, 15 540 Rhodochrosite ore, 15 589 Rhodococcus, as a host system for gene expression, 12 478 Rhodonite, 15 540 color, 7 331 Rhodopsin, 9 512 Rhoeadine, 2 90 Rhoedales... 

It triggers conformational changes in retinoid proteins, such as rhodopsin and bacteriorhodopsin, relevant to vision and ATP synthesis, respectively. 

Kniep R, Simon P (2007) Fluorapatite-Gelatine-Nanocomposites Self-Organized Morphogenesis, Real Structure and Relations to Natural Hard Materials. 270 73-125 Koenig BW (2007) Residual Dipolar Couplings Report on the Active Conformation of Rhodopsin-Bound Protein Fragments. 272 187-216 Komatsu K (2005) The Mechanochemical Solid-State Reaction of Fullerenes. 254 185-206 Kremsner JM, Stadler A, Kappe CO (2006) The Scale-Up of Microwave-Assisted Organic Synthesis. 266 233-278... 

A synthesis of prototypes for natural retinal-protein complexes has been attempted by Bayer and coworkers They attached retinal, which is the chromophoric group of the protein conqilexes rhodopsin and retinochrome, to a modified pdy-(ethylene oxide) and investigated the red shift of these complexes. To imitate the natural binding of the retind, oligopeptides with identical functional side chains were incorporated into the system. The red shift behaviour of this semisynthetic polymeric product was found to be the same as that of the natural product. 

K., Synthesis of retinals with eight- and nine-membered rings in the side chain. Models for rhodopsin photobleaching intermediates. J. Org. Chem., 58, 3533, 1993. 

Wada, A., Tsutsumi, M., Inatomi, Y, Imai, H., Shichida, Y, and Ito. M.. Retinoids and related compounds. Part 26. Synthesis of (llZ)-8,18-propano- and methano-retinals and conformational study of the rhodopsin chromophore, J. Chem. Soc., Perkin Trans. I. 2430, 2001. 

Docosahexaenoic acid has the potential to affect cell function by modulating two aspects of membrane proteins synthesis (particularly via transcriptional control) (Sellmayer et al., 1997) and structure (within the lipid milieu of the membrane). Although understanding the effect of DHA on proteins is still in its infancy, two examples, rhodopsin and protein kinase C (PKC), have been particularly well studied. The effect of DHA on rhodopsin is reviewed in detail in Chapter 2. 

Photochemical cis-trans isomerization is a major area of interest in modem photochemical research and is also studied as part of organic photochemistry. Photochemical cis-trans isomerization has a major role in many photobiological phenomena, such as vision (rhodopsin) [1], ATP synthesis (bacteriorhodopsin) [2], phototaxis (Chlamydomonas) [3], and other allied processes. It has practical application in industry [4-6], i.e., vitamin A and D processes. Furthermore, it is a likely candidate for many optoelectrical and optomechanical switching and storage devices [7]. In this chapter, mainly various aspects of cis-trans isomerization originating from the singlet excited state will be discussed. 

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