Price: A protein complex that holds chromosome copies together opens one of its rings to facilitate important processes in cell division. Scientists at Nagoya University, with colleagues at Kyoto University in Japan, have uncovered a mechanism that allows a protein complex to bind to DNA without impeding some of the important processes of cell division. Their findings, published in the journal Cell Reports, could further understandings of developmental disorders arising from mutations in the gene that codes for the complex. DNA condenses during cell division to form structures called chromosomes that are formed of two identical copies, called sister chromatids. These sister chromatids are bound together by proteins called cohesins, until it is time for them to be pulled apart and directed into the newly formed cells. Scientists know quite a bit about the structure and functions of cohesin, but some questions remain. For example, cohesin binding to chromosomes should form a structural impediment to the process of DNA replication, so why doesn't it?