About the Authors
National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, United States of America
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
The authors have declared that no competing interests exist.
Conceived and designed the experiments: OVG ARP. Performed the experiments: JHF BAS SOG MYL OVG. Analyzed the data: JHF BAS OVG ARP. Wrote the paper: ARP.