Dystrophin-related protein (DRP or utrophin) is an autosomal homologue of dystrophin, a membrane cytoskeletal protein encoded by the Duchenne muscular dystrophy gene. In contrast to dystrophin which is predominantly expressed in muscle, DRP is expressed in various tissues. Here we report the purification and biochemical characterization of DRP from lung which shows the highest levels of DRP expression among adult tissues. DRP was purified from the high alkaline extract of lung membranes using heparin-agarose column chromatography followed by anti-DRP immunoaffinity column chromatography. DRP was expressed in the cultured pulmonary artery endothelial cells. Expression of DRP in endothelial cells could explain its abundant expression in lung. In analogy to dystrophin of muscle cells, DRP could be playing an important role in the mechanical stress mechanisms of endothelial cells.
