Fig. 1

Structure prediction of the zebrafish α-GAL. (a1) homodimer structure of human α-GAL; (a2) homodimer structure of zebrafish α-GAL. The dimers are colored from N-terminal (blue) to C-terminal (red). The structure prediction shows that the zebrafish α-GAL folds in a pattern highly similar to its human counterpart. (b1) is the monomer of a human α-GAL enzyme showing the two domains, while (b2) is the zebrafish α-GAL enzyme showing the same structure. Domain 1, (β/α)8 barrel, extends through residues 32–330 in human (red) and 21–319 in zebrafish (red), and contains the active site, while domain 2 extends through residues 331–429 in human (green) and 320–409 in zebrafish (green) and contains antiparallel β strands. C: the superimposed structure of the two enzymes active sites and substrate binding site, with substrate specificity residues W36, D81, D82, Y123, K157, R216 in zebrafish and W47, D92, D93, Y143, K168, R227 in human, are fully conserved between the two species. The active sites D159 and D220 in zebrafish, D170, and D231 in humans are also conserved. The residues C131 and C161 zebrafish and C142 and C172 human help to stabilize the conformation of the substrate-binding site through the formation of disulfide bonds. The substrate-binding site boundaries E192 and Y196 in zebrafish correspond to E203 and Y207 in humans. Color ligands for zebrafish and human are shown in plate C. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)