Γ-Amanitin

γ-Amanitin (gamma-Amanitin) is a cyclic peptide of eight amino acids. It is an amatoxin, a group of toxins isolated from and found in several members of the mushroom genus Amanita, one being the death cap (Amanita phalloides) as well as the destroying angel, a complex of similar species, principally A. virosa and A. bisporigera. The compound is highly toxic, inhibits RNA polymerase II, disrupts synthesis of mRNA, and can be fatal.

Toxicity
Amatoxins selectively inhibit Eukaryotic RNA polymerase II by tightly to the enzyme and severely inhibits translocation along the DNA template; thus the synthesis of mRNA and proteins stops. Amatoxin consumption is characterized by a long asymptomatic period of a few hours (up to a day or more) followed by quick physiological decline due to acute hepatic and tubular necrosis. γ-Amanitin has been found to have similar levels of toxicity to other amatoxins such as α-Amanitin.