Ribosome display is a powerful tool for in vitro selection and simultaneous evolution of proteins. Except for screening antibodies, this system can also be used for affinity selection of non-antibody proteins. As a leader in the field of ribosome display, Creative Biolabs can provide this service with highly efficiency. Both the prokaryotic ribosome display and eukaryotic ribosome display systems can be used for the selection of non-antibody proteins.
For cell-based in vitro display technology, including phage display, yeast display, and bacterial display, the genetic information needs to be introduced into cells. This will usually limit the diversity present in the cells to below what has been present in the actual library of DNA molecules. Ribosome display is a cell-free system for the in vitro selection of proteins and peptides. This technique couples an individual nascent protein to its corresponding mRNA through the formation of stable protein-ribosome-mRNA (PRM) complexes. By screening PRM complex, phenotype and genotype are coupled. This permits the simultaneous isolation of a functional nascent protein, through affinity for a ligand, together with the encoding mRNA. The library size of our ribosome display system can reach up to 1014. Our ribosome display antibody libraries can produce antibodies with pM affinity, which is the highest affinity among all the in vitro display technologies.
Protein Selection Using Affinity Tags
Affinity tags are appended to proteins so that they can be purified from their crude biological source using an affinity technique. Creative Biolabs has developed a system that uses affinity tag for isolating PRM-complexes for proteins without being antibodies. We can offer several tags, e.g. Strep-tag II and His-tag for protein selection. The affinity tag can be fused to the N-terminus of the protein for ribosome display.
Figure 1. Schematic drawing of a PCR product and its corresponding mRNA used for ribosome display (Lamla and Erdmann 2001).
Selection of Peptides/Proteins Binding to Enzymes
Creative Biolabs can select peptides/proteins that bind to enzymes. For instance, we can identify an ideal V-domain scaffold of the human V-like extracellular domain of CTLA-4 that specifically binding to lysozyme with the eukaryotic rabbit reticulocyte lysate system. On the other hand, the ribosome display system can be utilized to generate cDNA library from which enzyme was specifically isolated by its substrate. Meanwhile, ribosome display system can be used for the selection of enzymatic activity as well.
Ribosome display is a powerful tool to display functional proteins for applications such as drug targets identification and protein function identification, as this system avoids the problems of cytotoxicity, soluble protein expression and secretion bias in cell-based systems. Coupled with advanced whole genome sequencing and high-throughput screening platform, it is possible to design whole genome cDNA libraries for high-throughput ribosome display. This automated process for proteomics applications permits library-versus-library screening and genome-wide analysis of protein-protein interactions.
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