Fig. 1.

Structure and sequence of T. brucei MCA2^C213G. General loop regions are shown in gray, the N-terminal region in cyan, α-helices in blue, and β-strands in red, apart from βA-βC, which is shown in purple. (A) Tertiary structure of the MCA2 monomer with the position of the catalytic dyad in yellow. (B) MCA2 sequence with the assigned secondary structure. The catalytic dyad is highlighted in red, and residues involved in the S1 pocket and samarium binding are shown in orange and cyan, respectively. Known cleavage sites (14) are highlighted (▼), and residues that are missing from the MCA2^C213G electron density are shown in light gray and with a dashed line.