The preimages of RNA secondary structures in sequence space are represented by graphs called neutral networks.
Common structures form extended neutral networks which span entire sequence space.
Pairs of networks approach each other closely at intersection points of the compatibele sets in which they are embedded. Eight years ago the existence of neitral networks and their intersection points was predicted by a mathematical analysis of sequence-structure relations based on random graph theory and computer simulations. The current proposal suggests to explore the distribution of refined properties, like accessibility of suboptimal stuctures, folding efficiences, and folding times, on neutral networks formed by sequences folding into identical mfe-secondary structures. The validity of this conjecture has direct consequences for the evolutionary design of biomolecules since it allows topevelop new search strategies. The mapping of RNA sequences into kinetically controlled structures will be investigated by extensive computer simulations and by a mathematical model in the spirit of the random graph approach to neutral networks of mfe-structures.