Description
NADPH Oxidase 4/NOX4, also known as Renal NADPH Oxidase/RENOX and Kidney Oxidase 1/KOX1, is a 66 to 75 kDa member of the NOX family of NADPH oxidases. NOX family members are a major source of reactive oxygen species (ROS), including hydrogen peroxide and superoxide, and are critical mediators of redox signaling. NOX4 is strongly expressed in the kidney, especially in the proximal convoluted tubule cells of the renal cortex, and may function as an oxygen sensor that regulates the synthesis of erythropoietin. Expression is also high in endothelial cells, and because aortas from deficient mice exhibit increased inflammation, hypertrophy and endothelial dysfunction, NOX4 may function to protect the vasculature during ischemic or inflammatory stress. Human NOX4 is 578 amino acids (aa) in length, with several additional smaller isoforms identified. Over aa 450-578, human NOX4 has 92% sequence identity with mouse NOX4, and 91% identity with rat NOX4