FIGURE 1.

Crystal structure of Ldt_Mt5. Left, apo-Ldt_Mt5; right, rotated 90°. Ldt_Mt5 is composed of two BIg domains and a CD. The semitransparent volume is surface-accessible by a 3.5-Å radius probe. Residues of the active site (His³⁴², Thr³⁵⁷, Asn³⁵⁸, and Cys³⁶⁰) are represented as sticks within the CD. Tryptophan residues of the CTSD are also represented as sticks and interact with a hydrophobic patch at the interface of the BIgB domain. The prominent outer cavity that is observed in Ldt_Mt2 is absent in apo-Ldt_Mt5 but is indicated as a reference (10). The Ldt_Mt5 secondary structure schematic is colored as a rainbow from blue (N terminus) to red (C-terminus). Orange dashes represent the disordered portion of loop L_C, and red dashes represent the disordered ex-CTSD. This figure was made using Chimera (19).