If using molecular replacement a starting model must be used for the collected data to be rotated and translated on to obtain a structure that will be refined / built into electron density / then refined in repetitive cycles to obtain the best fit possible between the data (electron density) and the improved (re-refined model). If the lab has a good idea of a starting structure the PDB file can be obtained from the Protein Data Bank, or from the World Wide Protein Data Bank.

If their is no structure available to do molecular replacement, either multiwavelength anomalous diffraction (MAD), or isomorphous heavy atom replacement will be needed to obtain phasing information to calculate starting electron density maps.

When a structure is obtained and is used in a publication, as supporting evidence to a scientific thesis, the publishing journal requires that the structural coordinates be released. There are rules which govern structure release, which allow author(s) some time past their original publication to review their structure before being released to all in the scientific community. The usual place for deposition is in the Protein Data Bank, or the World Wide Protein Data Bank.