Abstract
Sera of camelid species contain a special kind of antibody that consists only of heavy chains. The variable antigen binding domain of these heavy chain antibodies can be expressed as a separate entity, called a single domain antibody that is characterized by its small size, high solubility and oftentimes exceptional stability. Because of this, most single domain antibodies fold correctly when expressed in the reducing environment of the cytoplasm, and thereby retain their antigen binding specificity. Single domain antibodies can thus be used to target a broad range of intracellular proteins. Such intracellular single domain antibodies are also known as intrabodies, and have proven to be highly useful tools for basic research by allowing visualization, disruption and even targeted degradation of intracellular proteins. Furthermore, intrabodies can be used to uncover prospective new therapeutic targets and have the potential to be applied in therapeutic settings in the future. In this review we provide a brief overview of recent advances in the field of intracellular single domain antibodies, focusing on their use as research tools and potential therapeutic applications. Special attention is given to the available methods that allow delivery of single domain antibodies into cells.
Highlights
In 1993, a serendipitous discovery that led to the identification of a new type of antibody in the sera of camelid species was reported [1]
When VHH B99 was co-expressed with a Shoc2-S2G mutant, which impairs signaling through the ERK1/2 pathway, it could partially restore ERK1/2 phosphorylation. These results indicate that the Shoc2 epitope that is targeted by VHH B99 and B120 might be involved in a negative feedback loop that modulates ERK1/2 signaling
Many recent studies that focus on protein functionality have underlined the utility of intracellular VHHs as research tools
Summary
In 1993, a serendipitous discovery that led to the identification of a new type of antibody in the sera of camelid species was reported [1]. It was demonstrated that the serum of these mammals contains classical immunoglobulins (IgGs), and a second type of antibody that consists only of heavy chains. These so called heavy chain antibodies (HCAbs) make up 50–80% of the total serum IgG amount in camels and 10–25% in South-American camelids [2], suggesting that they play an important role in the humoral immune response of these animals. In the wake of the discovery of HCAbs in camelid sera, it was soon realized that the HCAb variable domain (VHH) could be expressed as a separate protein fragment, while retaining full antigen binding capacity [6]. VHHs are usually very stable, being able to resist chemical (e.g., 7 M guanidinium chloride or 10 M urea) and thermal denaturation (Tm is on average 60 ◦C or higher) [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
