The site-2 protease

AbstractThe site-2 protease (S2P) is an unusually-hydrophobic integral membrane protease. It cleaves its substrates, which are membrane-bound transcription factors, within membrane-spanning helices. Although structural information for S2P from animals is lacking, the available data suggest that cleavage may occur at or within the lipid bilayer. In mammalian cells, S2P is essential owing to its activation of the sterol regulatory element binding proteins (SREBPs); in the absence of exogenous lipid, cells lacking S2P cannot survive. S2P is also important in the endoplasmic reticulum (ER) stress response, activating several different membrane-bound transcription factors. Human patients harboring reduction-of-function mutations in S2P exhibit an array of pathologies ranging from skin defects to neurological abnormalities. Surprisingly, Drosophila melanogaster lacking S2P are viable and fertile. This article is part of a Special Issue entitled: Intramembrane Proteases

Polymerizable Ionic liquids as a dopent in polymer based photovoltaic devices employing a chemically fixed p-I-n junction

The high cost of silicon-based photovoltaic devices is currently limiting their promise as a viable replacement to fossil fuel. Recent research in polymer-based photovoltaics has received significant attention as a possible affordable solar energy technology. In particular, research on chemically fixed p-i-n junctions in polymer based thin film photovoltaics has shown promising results. These devices work by blending ionic monomers into a polymer film and placing them between two electrodes. These monomers respond to an applied bias resulting in electrochemical doping occurring at the electrodes ending with a fixed p-i-n junction. Devices demonstrate promising open circuit voltages but suffer from low power conversion efficiency and extensive charging time. Recently it was demonstrated in light-emitting electrochemical cells that substituting ionic monomers with polymerizable ionic liquids significantly reduces charge time without affecting device performance. Here, we use these PILs to create a fixed p-I-n junction photovoltaic device. These devices are demonstrating some of the highest open circuit voltages seen in polymer PV devices. We will discuss strategies for optimizing overall device performance in order to achieve a low-cost, high performance polymer photovoltaic technology