ARMER: Proteins and Enzymes

Apoptosis is important for normal development and tissue homeostasis. It is mediated by various caspases and ultimately results in the activation of endogenous endonucleases that degrade cellular DNA. Although apoptosis induced by endoplasmic reticulum (ER) stress is thought to be mediated by caspase-12, other caspases such as caspase-9 are also thought to be activated following ER stress. Recently, ARMER, a novel integral ER-membrane protein was shown to protect cells from ER stress-induced apoptosis. Analysis of the caspase proteolytic cascade suggests that ARMER acts by inhibiting caspase-9 activity (3), although the mechanism for this remains unkown. It should be noted that ARMER is not related to the inhibitor of apoptosis proteins (IAP) family and does not contain any baculoviral IAP repeat (BIR) domains.