Rhodopsin topology

Fig. 8.2 Topology of the hA3AR built using bovine rhodopsin as template...

The importance of environmental effects on the processes at and near CIs is illustrated by recent experimental studies of biologically relevant systems, e.g. the chro-mophores of the rhodopsin family [10,11] and other photoactive proteins [12-16] as well as the building blocks of DNA [17,18] some solution studies have also been undertaken [89-91], These studies reveal the crucial role of CIs and suggest that a solvent or protein environment can have a pronounced impact on the electronic structure and Cl topology and the net rate of passage to the ground state. 

The Ma, Znoiko, et. al. paper begins with a thought provoking Summary. They seek to show that the response of rods and cones cannot be correlated with a topological designation or by their putative associated transducins. The paper tends to use the term opsin, as opposed to rhodopsin. Although discussed indirectly, the conclusion can be... 

Search the Web site to predict transmembrane topology of rhodopsin with the following sequence and compare the membrane-spanning regions with the hydrophobicity profiles of ProScale... 

Only recently was the first higfr-resolution atomic structure of a G-protein-coupled receptor solved, namely that of rhodopsin, although lower-resolution spatial structural information based on two-dimensional crystals and electron diffraction and NMR structures was available.3.4 This information makes it certain that all heptahelical receptors have the same topological arrangement of the polypeptide chains. The amino- and carboxy-termini are oriented in the same way, with the amino-terminus outside and carboxy-terminus on the cytoplasmic side. Valuable structural relationships between different G-protein-coupled receptors for hormones have also come to light, mainly thanks to comparisons of cDNA-derived sequences. ... 

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