Acetylcholine Receptor (IMAGE) University of Pennsylvania School of Medicine Caption Myasthenia gravis is caused by an autoimmune response to the acetylcholine receptor (pictured here), a muscle protein that translates nervous system signals into muscle contractions. Credit Drawing courtesy of Jon Lindstrom, PhD, Perelman School of Medicine, University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.