Diffractogram tableaux by mouse click.

A computer program written in "Java" is presented, which calculates the diffractogram tableaux and the wave aberrations of electron microscopes. This program can be used interactively for alignment and measuring the optical data of any electron microscope.

Ribosome interactions of aminoacyl-tRNA and elongation factor Tu in the codon-recognition complex.

The mRNA codon in the ribosomal A-site is recognized by aminoacyl-tRNA (aa-tRNA) in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here we report the 13 A resolution three-dimensional reconstruction determined by cryo-electron microscopy of the kirromycin-stalled codon-recognition complex. The structure of the ternary complex is distorted by binding of the tRNA anticodon arm in the decoding center.

Structure of the 13-fold symmetric portal protein of bacteriophage SPP1.

We have determined the three-dimensional structure of bacteriophage SPP1 portal protein (gp6) using electron microscopy at liquid-helium temperatures and angular reconstitution. The 13-fold symmetric gp6 oligomer is a turbine-shaped structure with three distinct regions: a conical stem with a central channel; the turbine wings region; and a fringe of small 'tentacles' at the end of the channel exposed to the viral head interior. The tentacle region appears flexible and may be associated with a particular function - sensing when the correct amount of DNA has been packaged.

Stress-induced recrystallization of a protein crystal by electron irradiation.

Ordering of a system of particles into its thermodynamically stable state usually proceeds by thermally activated mass transport of its constituents. Particularly at low temperature, the activation barrier often hinders equilibration--this is what prevents a glass from crystallizing and a pile of sand from flattening under gravity. But if the driving force for mass transport (that is, the excess energy of the system) is increased, the activation barrier can be overcome and structural changes are initiated.

Correlation of the expansion segments in mammalian rRNA with the fine structure of the 80 S ribosome; a cryoelectron microscopic reconstruction of the rabbit reticulocyte ribosome at 21 A resolution.

Samples of 80 S ribosomes from rabbit reticulocytes were subjected to electron cryomicroscopy combined with angular reconstitution. A three-dimensional reconstruction at 21 A resolution was obtained, which was compared with the corresponding (previously published) reconstruction of Escherichia coli 70 S ribosomes carrying tRNAs at the A and P sites. In the region of the intersubunit cavity, the principal features observed in the 70 S ribosome (such as the L1 protuberance, the central protuberance and A site finger in the large subunit) could all be clearly identified in the 80 S particle.