"Everything should be made as SIMPLE as possible, but no simpler"
We have replaced the common lines-based routines with a new ab initio reconstruction method PRIME (PRobabilistic Initial 3D Model Generation for Single-Particle Cryo-Em).
What does PRIME do?
*) PRIME can, in a single step, generate an initial 3D map directly from the noisy images
*) PRIME can overcome model bias introduced by an erroneous initial map, see movie above:
Alignment of 5000 ribosome cryo-EM images (Frank, 2009) using an unrelated molecule, RNA polymerase II, as the initial 3D model. The movie shows the progress of the reconstruction from starting model to converged map. The view is selected to show the interface between the 30S (small) and 50S (large) subunit of the ribosome, where the tRNA:s bind.
More examples can be found here.
*) PRIME will be extended for heterogeneity analysis and high-resolution refinement (coming soon)
SIMPLE 1.0 can be found here.