KP4 specifically inhibits voltage-gated calcium channels inhibiting
cell growth and division by blocking calcium import.
The KP4 gene is derived from the genome of a double-stranded RNA
virus (Ustilago Maydis Virus 4, UmV4, Totiviridae, Totivirus,
00.075.0.01), which is present in the tissue of certain fungal
strains of corn smut (Ustilago maydis). Expression of the KP4 gene
leads to the production of the KP4 (killer protein 4).
In Ustilago maydis cells KP4 leads to a reversible inhibition of
hyphal growth, but does not kill off competing strains. It is
expected that plants expressing the KP4 protein are less
susceptible to damage caused by the phytopathogenic fungi Ustilago