Blocks Kv11/ERG potassium channels (tested in MMQ lactotroph cells that contain the three ERG channels: rKv11.1/KCNH2/ERG1, rKv11.2/KCNH6/ERG2 and rKv11.3/KCNH7/ERG3). This toxin can be used to distinguish slow deactivating components (ERGS) from fast deactivating components (ERGF) currents, since it specifically blocks ERGS. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Has the CSalpha/beta fold, which comprises one or two short alpha helices connected to anti-parallel beta-sheets stabilized by three or four disulfide bonds. Belongs to the ergtoxin family. Gamma-KTx 3 subfamily.