This family contains both neurotoxins and plant defensins. The mustard trypsin inhibitor, MTI-2, is plant defensin. It is a potent inhibitor of trypsin with no activity towards chymotrypsin. MTI-2 is toxic for Lepidopteran insects, but has low activity against aphids [1]. Brazzein is plant defensin-like protein. It is pH-stable, heat-stable and intensely sweet protein [2]. The scorpion toxin (a neurotoxin) binds to sodium channels and inhibits the activation mechanisms of the channels, thereby blocking neuronal transmission. Scorpion toxins bind to sodium channels and inhibit the activation mechanisms of the channels, thereby blocking neuronal transmission

1: Selection by phage display of a variant mustard trypsin inhibitor toxic against aphids. Ceci LR, Volpicella M, Rahbe Y, Gallerani R, Beekwilder J, Jongsma MA; Plant J 2003;33:557-566. PMID:12581313

2: Sweetness determinant sites of brazzein, a small, heat-stable, sweet-tasting protein. Assadi-Porter FM, Aceti DJ, Markley JL; Arch Biochem Biophys 2000;376:259-265. PMID:10775411