About the Authors
California Institute of Technology, Pasadena, California, United States of America
Howard Hughes Medical Institute, Division of Biology, Pasadena, California, United States of America
Dipartimento di Biologia, University of Pisa, Pisa, Italy
The authors have declared that no competing interests exist.
The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: MP GJJ. Performed the experiments: MP. Analyzed the data: MP GJJ. Wrote the paper: MP GJJ. Performed immuno-EM staining and freeze-substitution: MSL. Performed cryo-sectioning: MSL AWM. Performed phylogenetic analyses: MP GP.