New genotype-phenotype linkages for directed evolution of functional proteins

The key practical consideration in directed evolution of functional biomolecules is the linkage of genotype and phenotype. In vitro selections offer the potential to select from libraries with up to 1010-1014 members, with fewer constraints than current cell-based selections. New approaches such as mRNA display, ribosome display and in vitro compartmentalisation have complementary areas of application in selections for binding or catalysis.