1. BioCentrum Amsterdam, Institute for Molecular Cell Biology, Kruislaan 316, 1098 SM Amsterdam, The Netherlands,
2. Department of Electrical and Computer Engineering, University of California San Diego, Urey Hall Addition, Mail Code 0339, La Jolla, CA 92093–0339, U.S.A.,
3. Department of Chemistry, University of California San Diego, Urey Hall Addition, Mail Code 0339, La Jolla, CA 92093–0339, U.S.A.