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Figure 1
Structure of fetuin-B. (a) Topology scheme of mouse fetuin-B depicting strands as arrows (labeled β1–β13) and helices as rods (α1–α3), each with their delimiting residues. Domain CY1 is in orange, the linker (LNK) is in red, CY2 is in turquoise and the CTR is in purple. N-glycans are marked with blue lollipops and labeled. Disulfides are pinpointed as pale green lines and labeled: [\bigcirc \kern -.7em \scriptstyle 1], C39–C374; [\bigcirc \kern -.7em \scriptstyle 2], C96–C107; [\bigcirc \kern -.7em \scriptstyle 3], C120–C140; [\bigcirc \kern -.7em \scriptstyle 4], C154–C157; [\bigcirc \kern -.7em \scriptstyle 5], C217–C224; [\bigcirc \kern -.7em \scriptstyle 6], C237–C263. Missing segments are shown as dotted lines, and hairpins I and II of each cystatin domain are further labeled. (b) Ribbon-type plot of mouse fetuin-B, with each domain colored as in (a). N-glycans are labeled with an encircled `A' (N40) and `B' (N139); P155 and N156 from the CPDCP-trunk are labeled and their side chains are shown. The N- and the C-termini of the protein are labeled and residues from the purification tag are shown in pink. (c) The CPDCP-trunk featuring a rigid 14-atom ring (C atoms in gray). (d) Superposition of CY1 (orange), CY2 (cyan) and ovocystatin (purple; PDB entry 1cew; Bode et al., 1988BB9) as Cα plots. The respective type-A and type B-disulfides are shown in red and labeled, as are the legumain-binding loops in the three structures, hairpins I and II, and the N- and C-termini. (e) Superposition of the Cα traces of mouse fetuin-B: unbound (CY1 in yellow, LNK in green, CY2 in dark blue and CTR in pink) and in complex with astacin [domain colors as in (b)]. The inset shows a close-up showing the CPDCP-trunk, hairpin I and hairpin II in cross-eyed stereo. The observed differences may be authentic or may be the result of crystal contacts.

Volume 6| Part 2| March 2019| Pages 317-330
ISSN: 2052-2525