Specifically, we generated two independent GSN conformational ensembles through metainference multi-replica simulations, using experimental SAXS data as a restraint and the 1B mapping and parameters to compute the forward models. One of the two ensembles was obtained by enabling the SLC with a value of 0.08 and with the SC of 0.7 nm 2 . We selected these settings based on the result of the analyses reported in the previous paragraph: as well as being particularly appropriate for GSN, this combination was also reasonable for B1 and GFP (Table ). To define the ensembles, we considered only the second half of the trajectory of each replica, where the correlation between the forward model and the experimental intensity was stably close to 1, with a constant metainference score. From each ensemble we extracted 1,000 equally distant frames, recalculated the SAXS profile using PLUMED with 1B mapping and determined the average profile. For the ensemble frames with hydration layer correction, we used the same SLC and SC settings as for the refinement. The two average profiles, representing the two ensembles, were directly compared with the experimental SAXS data (Figure ). We observed that both profiles show good agreement with the experimental SAXS data, with a chisquared of 0.8 and 1.4 without and with SLC term, respectively. To verify that our hydration layer correction is working properly, we also calculated the SAXS intensities using the WAXSiS webserver and determined the corresponding average profiles. We compared the PLUMED profile with the WAXSiS profile of the ensemble obtained without SLC (Figure , left panel), and the PLUMED profile with the WAXSiS profile of the ensemble obtained with SLC (Figure , right panel). In this case, we found that the agreement between PLUMED and WAXSiS is higher when comparing the intensities calculated from the ensemble with SLC (RMSE: 1.7⋅10 -2 ) than when comparing the intensities calculated from the ensemble without SLC (RMSE: 6.4⋅10 - 2 ). This indicates that, although the hydration layer contribution in the SAXS intensity calculation is not critical to match the experimental data, hySAS can match WAXSiS with the appropriate SLC/SC settings. We analysed both the ensembles in terms of radius of gyration and root mean square fluctuations (RMSF) to gauge the effect of the SLC on the resulting conformations. Although both the ensembles showed a bimodal distribution of the radius of gyration, the one obtained with the inclusion of the SLC was, as possibly expected, more compact with an average radius of gyration of 3.05 nm, compared to the one generated without the SLC, which showed an average radius of gyration of 3.14 nm (Figure ). Interestingly, a similar behaviour was observed regarding the RMSF. The ensemble calculated applying the SLC shows systematically lower fluctuations, with an average RMSF of 0.26 nm, compared to the other ensemble, which has an RMSF of 0.38 nm (Figure , S6, S7). Focusing on the SLC corrected ensemble is clear that the main contribution to its lower radius of gyration and RMSF comes from the long N-terminal disordered region. Apart from this region, the system is compact and rigid with significant fluctuations only found in the two main linkers connecting the G2 domain to the G3 domain and the G3 domain to the G4 domain (Figure ). The ensemble closely resemble the crystal structure of the closed/inactive state, where rigid domains are also in agreement with the high resolution data for some of the isolated domains (also in the presence of Ca 2+ and/or actin) .