Ribosome display is a technology for library selection and simultaneous mol
ecular evolution in vitro. We present here a comparison between an optimize
d Escherichia coli system and different rabbit reticulocyte ribosome displa
y systems, optimized in a number of parameters, as a coupled eukaryotic sys
tem had been suggested to result in high enrichment factors [He and Taussig
(1997) Nucleic Acids Res. 25, 5132-5134], With all systems, antibody scFv
fragments, complexed to the ribosomes and the corresponding mRNA, were enri
ched by binding to their cognate antigen and enrichment was always dependen
t on the absence of a stop codon and the presence of cognate antigen. Howev
er, the efficiency of the E, coli ribosome display system was 100-fold high
er than an optimized uncoupled rabbit reticulocyte ribosome display system,
with separate in vitro transcription and translation, which was in turn se
veral-fold more efficient than the reported coupled system. Neither the E,
coil nor the rabbit reticulocyte ribosome display system was dependent on t
he orientation of the domains of an antibody scFv fragment or on the spacer
sequence, In summary, we could not detect any intrinsic advantage of using
a eukaryotic translation system for ribosome display. (C) 1999 Federation
of European Biochemical Societies.