Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.|Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.|Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.|Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.|Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.