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. Author manuscript; available in PMC: 2011 Jun 1.
Published in final edited form as: Arthritis Rheum. 2010 Jun;62(6):1630–1640. doi: 10.1002/art.27439

Figure 4.

Figure 4

Clustering of the potential citrullination sites in peptidyl arginine deiminase type 4 (PAD-4) into 3 distinct regions. A, Schematic representation of the secondary structure of PAD-4 (adapted from ref.24). The secondary structure elements in the N-terminal and C-terminal domains are shown in blue and yellow, respectively. Bars show -helices; arrows show β strands; and broken lines show disordered regions. The potential arginine targets for citrullination are shown in red. B, Tertiary structure of PAD-4, revealing clustering of citrullination sites into 3 distinct regions. The cluster comprising Arg-372, -374, -383, and -394 spans the active site cleft. The N-terminal and C-terminal domains are shown in blue and yellow, respectively, while the sites of arginine deimination are indicated in red. The model shown was generated from the Molecular Modeling Database (National Center for Biotechnology Information), according to coordinates generated by Arita et al (16). Adapted by permission from Macmillan Publishers Ltd: Nat Struct Mol Biol 2004;11(8):777–83. Copyright 2004.