Cyclopiazonic Acid, CPA, A potent Inhibitor of Intracelluar Ca2+ - ATPase Pump. Cyclopiazonic acid (CPA) is a toxic fungal secondary metabolite. Chemically, it is an indole tetramic acid. CPA was originally isolated from Penicillium cyclopium and subsequently from other P. cyclopium, Penicillium griseofulvum, Penicillium camembertii, Aspergillus flavus and Aspergillus versicolor.
CPA is a highly potent, selective and reversible inhibitor of the sarcoplasmic reticulum (ER) Ca2+ - ATPase pump (SERCA). This Ca2+ pump is an integral membrane protein of 994 amino acids that consists of three cytoplasmic domains containing the ATP binding site and ten transmembrane helices containing the two calcium binding sites.
The interchange of Ca2+ between the cell cytosol and the ER lumen by SERCA is a central process in intracellular signaling. Moreover, this process has a critical role at the muscle contraction-relaxation cycle, in which, the recovery phase relies on transport of calcium into the ER by the action of the SERCA. Inhibition of this pump leads to decrease of Ca2+ uptake from the cytosol to the ER Lumen, thereby depletion of Ca2+ store operated and increase of cytosolic Ca2+.
CPA inhibits the calcium pump by blocking the calcium access channel and immobilizing a subset of transmembrane helices.
Alomone Labs is pleased to offer Cyclopiazonic acid a natural toxin isolated from the Penicillium griseofulvum and purified to homogeneity. Cell Ca2+ Signaling; Intracellular Ca2+ Mobilizers.