Hedgehog (IMAGE) UT Southwestern Medical Center Caption Cryo-EM structures illuminate the molecular mechanism of Hedgehog signaling. 1. PTCH1 alone. 2. 1-to-1 ratio PTCH1-HH complex (Nature 560:128-132). 3. 2-to-1 ratio PTCH1-HH complex (Science doi/10.1126/science.aas8843). Credit The Li laboratory, UT Southwestern 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.