4MRNA is an abbreviation for “Massive Multi-type Model Molecular Replacement for Nucleic Acids”, with “4M” representing the four consecutive words beginning with “M”, “R” representing “Replacement”, and “NA” representing “Nucleic Acids”.

This is a new program that creates diverse models through parameter editing to overcome the difficulty of nucleic acid molecular replacement caused by the lack of suitable models. 

For more details, please see the “About” section. 

Before using 4MRNA, please complete a simple installation procedure. This software also depends on the external programs 3DNA, Phenix and Phaser, which must be installed beforehand. These installations are required only once before using the software for the first time. 

The installation procedure is described in the “Installation” section.

To run 4MRNA, simply type 4MRNA in the command line. After answering a few initial questions, you only need to wait for the process to finish. Once it is completed, you can proceed to structure refinement using your preferred method.

In addition, an advanced execution mode for expert users is also available. 

For detailed procedures, please refer to the “Usage” section.

If you use 4MRNA in your research, please cite the following reference. 

• Ando, S., & Kondo, J. (2026). 4MRNA: a new approach for nucleic acid molecular replacement using models with diverse parameter patterns. RNA, 32(10), 1544–1559. https://doi.org/10.1261/rna.081112.126