Ricin complexed with antibody V5G6, molecular model. The image shows two ricin chains (green, pink), the anti-RON nanobody (blue) and three glucopyranose residues. RON (Recepteur d'Origine Nantais) kinase is named after the French city in which it was discovered. It is related to the c-MET receptor tyrosine kinase. VHH stands for variable heavy homodimers A VHH antibody corresponds to the variable region of a heavy chain of a camelid antibody and has a very small size of around 15 kDa - hence the name nanobody.