Fig. 3: Major conformational changes of the D1 of dimeric suPAR (this work) compared to the ligand-bound suPAR (PDB 3BT2).

a D1 in the ligand-bound suPAR (cyan) forms a typical three-fingered fold with a palm region (circled) packed with highly conserved disulfide bridges. The three fingers of this fold are labeled F1-F3. b In dimeric suPAR, the D1 of one protomer (magenta, in an orientation similar to in a) has only two fingers with the β1F strand of the third finger swings away from the D1 pivoting on a hinge (residue 60–62, black dashed circle) of D1. The β1F strand, along with a long loop between the D1 and D2, forms a long expanded ring (residue 62–92, circled in the red dashed circle). c A 60°rotation along Y axis of the B orientation shows the β1E in D1 of dimeric suPAR (magenta) dislodges away, in parallel, from the first and the second fingers, leading to a shift of 18 Å, compared to the D1 of ligand-bound suPAR (shown in transparent cyan). d The expanded ring captures the β1C- β1D hairpin (green) of the other protomer of suPAR. Such interactions are the key for dimeric suPAR formation.