In terms of the extensive experience in single domain antibody (sdAb) discovery and development field, Creative Biolabs has built up a novel intrabody discovery platform to screen and validate novel single domain antibodies that can bind to intracellular targets specifically within various cellular compartments. Our professional scientists can utilize either the yeast or the mammalian two-hybrid system to screen the sdAb library and validate the specific intrabodies.
Within the biomedical and pharmaceutical communities, the antibodies specific for extracellular or cell surface targets are currently the fastest growing class of new therapeutic molecules. However, the majority of potential therapeutic targets are intracellular, while most antibodies cannot readily recognize such molecules because of the inability to form stable structures in the intracellular environment. During the past decade, the development of intracellular screening protocols and the definition of antibody structures that retain their antigen-binding function in an intracellular context have allowed the robust isolation of a subset of antibodies that can function in the intracellular environment. These antibodies, generally refer to as intrabodies, have immense potential in the process of drug development and may ultimately become therapeutic entities.
Compared with other conventional antibody formats (e.g. full length, Fab, scFv), single domain antibody which is an antibody fragment consisting of a single monomeric variable antibody domain, has indicated greater developability and manufacturability as a new candidate of intrabody discovery. As a novel antibody format, the comparatively low molecular mass of sdAb (~15 kDa) leads to a better permeability in tissues. Unlike full-length antibodies, sdAbs do not show complement system triggered cytotoxicity because they lack the Fc region. sdAbs derived from either camelid or cartilaginous fishes take advantage of high stability under extreme conditions (e.g. high temperature, acidic or alkaline condition). In addition, they are able to bind to hidden epitopes that are not accessible by conventional antibodies, for example to the active sites of enzymes. This property has been shown to result from their extended CDR3 loops, which contributes to penetrating such sites. However, because of the interior of the cell poses significant challenges regarding antibody folding, assembly, and functionality, the in vitro selection strategies cannot guarantee the identified sdAbs are suitable for the intercellular applications. As a solution to this gap, our advanced intrabody discovery platform can contribute to isolating specific sdAbs with intercellular functions. With efficient in vivo two-hybrid methods, our scientists are pleased to tailor the best-fit strategies to meet our clients’ demands.
Fig. 1 Schematic representation of yeast two-hybrid method.
Yeast two-hybrid is an in vivo genetic method that allows the detection of the binding partners in protein-protein interactions. Yeast has several characteristics that make it a robust organism to host the interaction, including the ability to form tertiary protein structures, neutral internal pH, enhanced ability to form disulfide bonds and reduced-state glutathione among other cytosolic buffer factors, to maintain a hospitable internal environment. Creative Biolabs is able to offer a high-throughput screening for the sdAb library to select potential intrabodies.
Compared to the yeast two-hybrid system, the mammalian two-hybrid system can closely mimic the native protein environment to investigate protein-protein interactions in vivo. The mammalian two-hybrid system takes advantage of the similar post-translational modifications of both sdAbs and the target. It can be a meaningful complement to validate selected intrabodies through a low-throughput but more precise manner.
Typical Features of Our Intrabody Discovery Service
Creative Biolabs convinced that collaborate with our customers is the best way to share our full knowledge and experience. Our seasoned scientists are pleased to offer custom services for our clients to stratify the specific needs and expectations of their valuable projects. If you are interested in discovering your own intrabodies, please feel free to inquiry us for more details.