Figure 4: Three-dimensional structures of spider-derived ICK peptides. Protein Data Bank ID numbers for NMR structures of (a) ProTx-I [31] and (b) GsMTx-4 [33] are 2M9L and 1TYK, respectively. 3D structure models of (c) GTx1-15 were constructed by homology modeling with ICM-PRO (Molsoft, La Jolla, CA) based on NMR structures of HnTx-IV (PDB: 1niy). (d) NMR structure of ProTx-II by Park et al. [35]. Reprinted with permission from [35]. Copyright: 2014 American Chemical Society. β-Sheets are indicated as green or black arrows and disulfide bonds are highlighted with yellow. Note: spider-derived ICKs have only two antiparallel β-sheets and three disulfide bonds except for ProTx-II which has only one β-sheet.