The fourth intracellular domain of G-protein coupling receptors: helicity, basicity and similarity to opsins

Abstract

The minimal size of the fourth intracellular domain of heptahelical G-protein coupling receptors (GPCRs) is close to 15 residues, and a juxtamembrane 15-residue segment is predicted as helical (Helix-8) in most of the receptors. Sequences of opsins, non-visual opsin-like (family A) GPCRs and Taste-2 receptors correspond with bovine rhodopsin at four positions in this tract. This is especially evident in monoamine receptors. In most GPCRs, the conserved juxtamembrane segment also has a large fraction of basic sidechains, and a considerable excess of cationic over anionic residues. The conservation is not dependent on the preferred G-protein α subunit or the overall length of the domain, indicating an additive speciation. In rod opsins and some A-GPCRs this segment has been shown to associate with the bilayer and to interact with G-proteins. The segment could also be involved in precoupling of receptors and transducers. These interactions could be helped by both the structural propensities and the high content of cationic sidechains.

DOI: 10.1007/s00726-009-0316-x

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Cite this paper

@article{Parker2009TheFI, title={The fourth intracellular domain of G-protein coupling receptors: helicity, basicity and similarity to opsins}, author={Michael S. Parker and Steven L. Parker}, journal={Amino Acids}, year={2009}, volume={38}, pages={1-13} }