# 5. Input data description

## 5.1. Map

Modeling means atomic interpretation of a map. This map can be the result of our own reconstruction process or can be obtained from a database. In this tutorial we use the haemoglobin map EMD-3488, that can be downloaded from PDBe (Fig. 5.1).
WARNING In case you use your own map obtained from cryo-EM images: Take into account that cryo-EM 3D maps benefit significantly of an “optimizing” step, normally referred to as “sharpening” or “density improvement“, that tends to increase signal at medium/high resolution. Therefore, we recommend to sharp the map before tracing the atomic model. Either two Scipion protocols consecutively applied, xmipp3-local MonoRes and xmipp3-localdeblur sharpening , or the protocol xmipp3-deepEMhancer , allow map sharpening. Details about the parameters of these protocols are shown in Appendices Local MonoRes, Local Deblur Sharpening and DeepEMhancer Sharpening, respectively.

Once downloaded the volume, unpack it (command line: gunzip emd-3488.map.gz) and save it in your tutorial folder.

## 5.2. Sequences

The sequences of Hgb \alpha and \beta subunits are included in UniProtKB. Accession numbers are P69905 and P68871, respectively. Next, we show both sequences in fasta format:

>sp|P69905|HBA_HUMAN Haemoglobin subunit alpha