Brefeldin A

Brefeldin A is a cell permeable fermentation product from Penicillium brefeldianum. It is a lactone antibiotic and ATPase inhibitor for protein transport with an IC₅₀ of 0.2 μM in HCT 116 cells. Brefeldin A has been widely used as specific inhibitor of protein translocation from endoplasmic reticulum to Golgi. It blocks secretion and prevents the assembly of non-clathrin-coated buds on Golgi cisternae. Brefeldin A also inhibits guanine nucleotide-exchange proteins BIG1 and BIG2, activators of ADP-ribosylation factors. It induces apoptosis independently of p53 and  activates sphingomyelin metabolism.