Michael Radermacher

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The SPIDER system has evolved into a comprehensive tool set for image processing, making use of modern graphics interfacing in the VMS and UNIX environment. SPIDER and WEB handle the complementary tasks of batch processing and visualization of the results. The emphasis of the SPIDER system remains in the area of single particle averaging and reconstruction,(More)
Solving the structure of macromolecular complexes using transmission electron microscopy can be an arduous task. Many of the steps in this process rely strongly on the aid of pre-existing structural knowledge, and are greatly complicated when this information is unavailable. Here, we present two software tools meant to facilitate particle picking, an early(More)
The nuclear pore complex spans the nuclear envelope and functions as a macromolecular transporter in the ATP-dependent process of nucleocytoplasmic transport. In this report, we present three dimensional (3D) structures for both membrane-associated and detergent-extracted Xenopus NPCs, imaged in frozen buffers by cryo-electron microscopy. A comparison of(More)
We present a new reconstruction method that takes advantage of the fact that many biological macromolecular assemblies show a preferred orientation with respect to the plane of the specimen grid in the electron microscopic preparation. From one micrograph taken of such a specimen tilted by a large angle, a conical tilt series with random azimuthal angles(More)
Isolated skeletal muscle ryanodine receptors (RyRs) complexed with the modulatory ligands, calmodulin (CaM) or 12-kDa FK506-binding protein (FKBP12), have been characterized by electron cryomicroscopy and three-dimensional reconstruction. RyRs are composed of 4 large subunits (molecular mass 565 kDa) that assemble to form a 4-fold symmetric complex that,(More)
Single particles embedded in ice pose new challenges for image processing because of the intrinsically low signal-to-noise ratio of such particles in electron micrographs. We have developed new techniques that address some of these problems and have applied these techniques to electron micrographs of the Escherichia coli ribosome. Data collection and(More)
The calcium release channel (CRC) from skeletal muscle is an unusually large tetrameric ion channel of the sarcoplasmic reticulum, and it is a major component of the triad junction, the site of excitation contraction coupling. The three-dimensional architecture of the CRC was determined from a random conical tilt series of images extracted from electron(More)
Cotranslational translocation of proteins requires ribosome binding to the Sec61p channel at the endoplasmic reticulum (ER) membrane. We have used electron cryomicroscopy to determine the structures of ribosome-channel complexes in the absence or presence of translocating polypeptide chains. Surprisingly, the structures are similar and contain 3-4(More)
The ribosome is formed by assembly of proteins and nucleic acids, and synthesizes proteins according to genetic instructions in all organisms. Many of the biochemical steps of this fundamental process are known, but a detailed understanding requires a well-defined structural model of the ribosome. Electron microscopy combined with image reconstruction of(More)
The type II chaperonin CCT (chaperonin containing Tcp-1) of eukaryotic cytosol is a heteromeric 16-mer particle composed of eight different subunits. Three-dimensional reconstructions of apo-CCT and ATP-CCT have been obtained at 28 A resolution by cryo-electron microscopy. Binding of ATP generates an asymmetric particle; one ring has a slightly different(More)