RELIONi

RELIONi is a software package designed for cryo-electron microscopy (cryo-EM) image processing. It is widely used for reconstructing three-dimensional (3D) structures of biological macromolecules from electron micrographs. RELIONi, which stands for Real-space refinement using iterative and non-linear optimization, employs a Bayesian approach to particle picking, 2D classification, 3D classification, and 3D refinement.

The software allows researchers to process large datasets of cryo-EM images, identifying and aligning individual particle images, and then combining these aligned images to generate a high-resolution 3D map. Key features of RELIONi include its ability to handle heterogeneous samples, resolve conformational flexibility, and achieve near-atomic resolution. It has been instrumental in the determination of numerous protein structures that were previously difficult or impossible to solve using other techniques.

RELIONi is known for its user-friendly interface and its continuous development, incorporating new algorithms and improvements based on user feedback and advancements in the field. Its modular design facilitates integration with other cryo-EM software tools. The package is freely available for academic use, contributing to its widespread adoption in structural biology research laboratories worldwide.