Organization of rhodopsin molecules in native membranes of rod cells–an old theoretical model compared to new experimental data

Abstract

It has been shown that rhodopsin forms an oligomer in the shape of long double rows of monomers. Because of the importance of rhodopsin as a template for all G protein-coupled receptors, its dimeric, tetrameric and higher-oligomeric structures also provide a useful pattern for similar structures in GPCRs. New experimental data published recently are discussed in the context of a proposed model of the rhodopsin oligomer 1N3M deposited in the protein data bank. The new rhodopsin structure at 2.2 A resolution with all residues resolved as well as an electron cryomicroscopy structure from 2D crystals of rhodopsin are in agreement with the 1N3M model. Accommodation of movement of transmembrane helix VI, regarded as a major event during the activation of rhodopsin, in a steady structure of the oligomer is also discussed. [Figure: see text]. Superimposition of the 1U19 (red wire), 1GZM (purple wire) and 1N3M (blue wire) rhodopsin structures. Size of the wires is proportional to thermal factors of backbone C(alpha) atoms, view parallel to the membrane.