We built a model of the extracellular domain from the cryo-EM experimental structure of a homomeric zebrafish α1 glycine receptor in a desensitised state with a resolution of 3.10 Å (PDB entry: 6PM5). Glycine is bound in all five equivalent pockets. The ECD of the open and the more stable desensitized structure of the GlyR are very similar with differences in the two states confined to the transmembrane domain. The opening of the channel requires interactions of the ECD and the TMD domains, which occur at time-scale inaccessible to all-atom MD simulations. Consistent with other studies of pLGICs focused on binding, we limited our analysis to the extracellular domain (ECD), which contains the primary binding pockets of interest. The ECD model contains 218 residues per subunit, including the whole ECD structure and one residue of the pre-M1 helix; the last five residues of each subunits were restrained during the MD simulations to mimic the anchor effect of the TMD, as in previous ECD simulations. Hydrogen atoms were added using the web server H++ at neutral PH. Crucial disulphide bonds (forming the Cys-loop characterizing the pLGIC superfamily GlyR belongs to)