ProTx-III

ProTx-III (µ-TRTX-Tp1a; belongs to NaSpTx family 1) has been isolated from the venom of the Peruvian green-velvet tarantula Thrixopelma pruriens at the University of Queensland (Australia) . ProTx-III has been described to be a selective inhibitor of Nav1.7 with an IC50 value around 2 nM. The synthetic version of Tp1a produced by Smartox yields similar results in terms of Nav1.7 inhibition (see Figure 1) . Queensland scientists have described that ProTx-III induces no significant changes in the voltage dependence of activation or steady-state inactivation of Nav1.7. ProTx-III also inhibits Nav1.1, Nav1.2 and Nav1.6 at nanomolar concentrations and does not affects Cav channels and nicotinic acetylcholine receptors. ProTx-III demonstrates analgesic properties in vivo when injected intraplantary in mice prior treatment with OD1, an activator of Nav1.7, which induces spontaneous pain.