Crystals of Native and Modified Bovine Rhodopsins and Their Heavy Atom Derivatives

Rhodopsin, the pigment protein responsible for dim-light vision, is a G protein-coupled receptor that converts light absorption into the activation of a G protein, transducin, to initiate the visual response. We have crystallised detergent-solubilised bovine rhodopsin in the native form and after chemical modifications as needles 10–40 μm in cross-section. The crystals belong to the trigonal space group P31, with two molecules of rhodopsin per asymmetric unit, related by a non-crystallographic 2-fold axis parallel with the crystallographic screw axis along c (needle axis). The unit cell dimensions are a=103.8 Å, c=76.6 Å for native rhodopsin, but vary over a wide range after heavy atom derivatisation, with a between 101.5 Å and 113.9 Å, and c between 76.6 Å and 79.2 Å.