Working Model (IMAGE) Chinese Academy of Sciences Headquarters Caption Origin selection: H2A.Z nucleosomes bind Suv420H1 directly to establish H4K20me2 on chromatin, which then recruits ORC1 to bind to replication origins; Origin firing: H2A.Z-Suv420H1-H4K20me2-ORC1 axis selectively license and activate early replication origins. Credit Image by Dr. LI Guohong's lab 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.