ProTx-I

Protoxin I (ProTx-I; β-theraphotoxin-Tp1a) is a toxin that was originally isolated from the venom of Thrixopelma pruriens (Peruvian green velvet tarantula) . This toxin reversibly inhibits the tetrodotoxin (TTX) -resistant channel Nav1.8 (IC50 = 27 nM) and Nav1.2, Nav1.5 and Nav1.7 with IC50 values between 50 and 100 nM. Furthermore, ProTx-I shifts the voltage dependence activity of T-type Cav3.1 channels (IC50= 50 nM) without affecting the voltage dependence of inactivation. ProTx-I is a valuable tool to discriminate between Cav3.1 and Cav3.2