ACKNOWLEDGEMENTS
This work was partially supported by the US National Institute of General Medical Sciences (NIGMS/NIH) grant R01GM100482 (AK) and R35 GM141918 (to GTM); Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/S007105/1 (to DJR), and EMBO Installation Grant No: 4421 (to EK). Many thanks to the experimentalists who provided the ensemble targets.