GrTx1 is a peptide toxin originally isolated from the venom of the spider Grammostola rosea. GrTx1 blocks sodium channel , with IC 50 s of 0.63 µM, 0.23 µM, 0.77 µM, 1.29 µM, 0.63 µM and 0.37 µM for Nav1.1, Nav1.2, Nav1.3, Nav1.4, Nav1.6 and Nav1.7, repectively.GrTx1 can be used for neurological disease research.