Fig.: Overview Nanobodies
A Schematic comparison between conventional IgG and heavy chain only antibodies (HCAbs) and derived recombinant antibody formats. While IgGs have two epitope binding domains (VH & VL) involved in antigen binding, HCAbs require only one variable domain (VHH). With a molecular weight of 15 kDa and a dimension of 2 x 4 nm, VHH is the smallest naturally occurring antigen binding moiety and thus also referred as “Nanobody” (Nbs).
B After selection of Nbs by in vitro display technologies, purified Nbs can be functionalized depending on the purpose, e.g. by radioactive or fluorescent labeling, coupling to an enzyme or biotinylation. This makes Nbs very versatile and reliable tools for a variety of applications in biomedical research.
C For visualization of endogenous antigens in live cells, Nbs can be genetically fused to fluorescent proteins and introduced as DNA-encoded expression constructs in living cells. Reflecting their chimeric structure these constructs are termed “chromobodies, CBs”. CBs are emerging tools to visualize and monitor spatiotemporal dynamics of endogenous target using quantitative live cell imaging.