This protein is lethal to sensitive cells of the same or related species. It specifically inhibits voltage-gated calcium channels. It inhibits cell growth and division by blocking calcium import. Monomer. The KP4 toxin expressed in transgenic plant can render them resistant to KP4-susceptible fungal pathogens such as grass smut fungi. Successful tests have been made in tobacco and wheat. Was originally thought to be glycosylated, but this does not seem to be the case according to PubMed:8145639.