Mouse Anti-Human Podoplanin monoclonal antibody, clone JID761

Podoplanin is a type I small mucin-like protein involved in cell motility. We have identified and studied the podoplanin coding sequence in 201 species of vertebrates, ranging from cartilaginous fishes to mammals. The N-terminal signal peptide is coded by the first exon; the transmembrane and intracellular domains are coded by the third exon (except for the last amino acid, coded in another exon with a long 3'-UTR). The extracellular domain has undergone variation during evolutionary time, having a single exon in cartilaginous fishes, teleosts, coelacanths and lungfishes. In amphibians, this single exon has been split in two, and in amniotes, another exon has been acquired, although it has been secondarily lost in Squamata. The podoplanin evolutionary tree agrees with the species tree in most cases. Two functional elements in the proteins, the GXXXG dimerization motif in the transmembrane domain and the region where podoplanin is cleaved by gamma-secretase are subjected to positive selection.

An affinity tag system requires both high affinity and specificity. The RAP tag epitope DMVNPGLEDRIE, derived from rat podoplanin (PDPN), is specifically recognized by PMab-2 monoclonal antibodies in rats. Here, we demonstrated that high levels of PMab-2 can be produced inNicotiana benthamianaand plant-derived PMab-2 possesses similar activity to CHO-derived PMab-2, and the RAP tag presents a useful tagging system for detecting and purifying proteins from plant cells. The heavy chain of PMab-2 fused with KDEL, an endoplasmic reticulum retention sequence, and the light chain of the antibody were introduced intoN. benthamianaby agroinfiltration. The expression of PMab-2 peaked 4 days after agroinfiltration, and approximately 0.3 mg/g fresh weight of the antibody was accumulated. After purification, the plant-derived PMab-2 successfully recognized rat PDPN expressed in CHO-K1 cells and exhibited almost the same binding activity as CHO-derived PMab-2. The RAP-tagged proteins expressed in plant cells were specifically recognized by PMab-2. These results indicate that PMab-2 can accumulate at high levels inN. benthamianaand is easily purified and that the RAP tagging system presents a useful tool for detecting and purifying proteins of interest in plant cells.