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. Author manuscript; available in PMC: 2014 Mar 5.
Published in final edited form as: Biochemistry. 2013 Feb 21;52(9):1547–1558. doi: 10.1021/bi301008r

Figure 6.

Figure 6

Structural alignment of hCLD and the cysteine protease inhibitor Cystatin C. Backbone atoms of hCLD were superimposed on monomeric human Cystatin C in the unliganded state (PDB code: 3GAX). hCLD is shown in green, Cystatin C in yellow and, in both, the N-terminus is colored in red. Four additional residues at the N-terminus of hCLD as remnants of the cleavage by thrombin are colored in grey. The crystal structure of monomeric human cystatin C stabilized against aggregation was chosen for comparison since in all crystal structures of Cystatin C studied to date, the protein has been found to form 3D domain-swapped dimers, created through a conformational change of a beta-hairpin loop, L1 (68, 88–90). 3D domain swapping free structure defines the conformation of loop L1, which is essential for the inhibition of papain-like cysteine proteases.