D. Model for domain movements in the AAA ring of dynein during ATP hydrolysis at AAA1. The AAA ring can be divided into two halves that are connected by two springs. Upon ATP binding / hydrolysis, the gap between AAA1/ AAA2 closes and moves AAA6 / AAA5 which in turn pulls on AAA4 so that the gap between AAA4 / AAA5 closes as well. In addition, this conformational change will pull the buttress and therewith change the stalk registry. 