All tags RabMAb Diverse/novel epitope recognition, the sixth RabMAb® advantage

Diverse/novel epitope recognition, the sixth RabMAb® advantage

The rabbit’s immune system develops affinity differently than a mouse.

These differences are largely attributed to the rabbit’s lower immune dominance and larger B-cell repertoire. The benefit is a wider epitope recognition during antibody development. An example of this can be seen below, a comparison of rabbit and murine immune responses which shows that rabbit antisera recognizes a wider range of epitopes than mouse antibodies in a western blot analysis.

Our experience in antibody development has demonstrated that the rabbit immune system will generally yield a wider range of antibodies recognizing unique epitopes.

RabMAb vs mouse monoclonal comparison

Additionally, many major relevant human protein targets are highly conserved between mouse and human. Therefore, these proteins tend to be less immunogenic when using mouse or rat as a host.

By using a rabbit as a host with its unique mechanism of immune diversification and affinity maturation, RabMAb primary antibodies can be produced to a wider range of epitopes, allowing for discovery of more novel antibody targets.

Case study: Thiophosphate Ester RabMAb primary antibody [51-8] (ab92570)

Protein phosphorylation is the most widespread and studied regulatory signaling mechanism that occurs in both eukaryotic and prokaryotic organisms. This mechanism of adding phosphate (PO4) to a protein by a kinase forms the basis of cell signaling networks, from controlling of various protein properties (e.g. function, structure) and to being involved in all fundamental cellular processes (1, 2, 3).

However, the biochemical identification of the substrates of kinase of interest (KOI) has been challenging and limited. This is due to the low abundance of most phosphoproteins, and the low affinity and substoichiometry phosphorylation of kinase-to-substrate interaction (1, 4).

To address this limitation, a bio-orthogonal affinity purification and identification of direct kinase substrates has been introduced (6).

First, KOI accepts ATPγS, then it is allowed to thiophosphorylate its direct substrates. Second, the thiophospholyation site on the substrates is alkylated with p-nitrobenzylthiophosphate (PNBM). Finally, a thiophosphate ester specific rabbit monoclonal antibody (clone 51-8) is introduced to identify the tagged substrates (a diagram of the process mentioned in Nature methods 2007 paper).

This semi-synthetic epitope tagging provides a new way to identify and isolate the substrates of various kinases (4, 5, 6).

This novel RabMAb primary antibody can be used to detect kinase substrates containing thiophosphate esters following the kinase reaction as described by J. Allen and colleagues in Nature methods 2007 (see figure below).

This RabMAb primary antibody allows researchers to follow this approach to study kinase-substrate relationships of interest. The antibody is also context independent in that it can recognize serine, threonine, and tyrosine thiophosphorylated residues in a multitude of kinase phosphorylation consensus motifs (6).

Download the white paper: A semi-synthetic approach for tagging and identifying novel kinase substrates utilizing a thiophosphate ester specific monoclonal antibody, clone 51-8

A semi-synthetic approach for tagging and identifying novel 
kinase substrates utilizing a thiophosphate ester specific 
monoclonal antibody, clone 51-8
Thiophosphate ester


  • 1. Johnson, S.A. and Hunter, T. Nature Methods 2, 17–25, 2005.
  • 2. Hunter, T. Signaling−2000 and beyond. Cell 100, 113−127, 2000.
  • 3. Cozzon, A.J. Ann. Rev. Microbiol. 42, 97–125, 1988.
  • 4. Cai, D, Article Review, Mol. BioSyst., 3, 516 – 517, 2007.
  • 5. Allen, J.J. et al. J. Am. Chem. Soc., 127(15), 5288–5289, 2005.
  • 6. Allen, J.J. et al. Nature Methods, 4(6), 511–516, 2007. (PubMed)