Theoretical Biology and Bioinformatics, University of Utrecht, Utrecht, The Netherlands. m.a.c.groenenboom@bio.uu.nl|Theoretical Biology and Bioinformatics, University of Utrecht, Utrecht, The Netherlands. m.a.c.groenenboom@bio.uu.nl|Theoretical Biology and Bioinformatics, University of Utrecht, Utrecht, The Netherlands. m.a.c.groenenboom@bio.uu.nl