[Electron microscopy for the studies of membrane transport proteins].
Electron microscopy gives the real images of individual protein molecules, providing unique means in the structural research of membrane-transport proteins. Various techniques for the preparation of specimens for transmission electron microscopy were briefly described. Emphases were put on the recent progress of quick-freeze cryo-electron microscopy, including cryotransfer and freeze-fracture deep-etch replication. Exploiting the advantage of the latter technique, we visualized the in situ structure of inositol 1,4,5-trisphosphate receptor molecules in the smooth-surfaced endoplasmic reticulum (sER) membrane of the Purkinje neuron in bovine cerebellum. The tetrameric receptor molecules were unexpectedly small and formed a two-dimensional crystalline array on the surface of the cisternal stacks derived from sER. Its structural characteristics were discussed in comparison with the ryanodine-receptor, the other intracellular Ca2+ -channel.
Department of Fine Morphology, Institute of Medical Science, The University of Tokyo, Japan.
E
E
Katayama
D000818:Animals; D001921:Brain / Q000378:metabolism; D015220:Calcium Channels / Q000648:ultrastructure; D002352:Carrier Proteins / Q000648:ultrastructure*; D002417:Cattle; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000648:ultrastructure; D018160:Receptors, Cytoplasmic and Nuclear / Q000648:ultrastructure; D016628:Replica Techniques; D019837:Ryanodine Receptor Calcium Release Channel
D015220:Calcium Channels; D002352:Carrier Proteins; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009124:Muscle Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D019837:Ryanodine Receptor Calcium Release Channel