The 12CA5 monoclonal antibody recognizes the 9-amino acid sequence YPYDVPDYA, derived from influenza virus hemagglutinin (HA). HA is commonly added to proteins of interest using recombinant DNA technology. The HA tag can then be used for detection or purification of the tagged protein.

READYTAG ANTI-HA (CLONE: 12CA5)

Soong, R. S., et al. (2013). “Xenogeneic human p53 DNA vaccination by electroporation breaks immune tolerance to control murine tumors expressing mouse p53.” PLoS ONE 8(2): e56912. PubMed

The pivotal role of p53 as a tumor suppressor protein is illustrated by the fact that this protein is found mutated in more than 50% of human cancers. In most cases, mutations in p53 greatly increase the otherwise short half-life of this protein in normal tissue and cause it to accumulate in the cytoplasm of tumors. The overexpression of mutated p53 in tumor cells makes p53 a potentially desirable target for the development of cancer immunotherapy. However, p53 protein represents an endogenous tumor-associated antigen (TAA). Immunization against a self-antigen is challenging because an antigen-specific immune response likely generates only low affinity antigen-specific CD8(+) T-cells. This represents a bottleneck of tumor immunotherapy when targeting endogenous TAAs expressed by tumors. The objective of the current study is to develop a safe cancer immunotherapy using a naked DNA vaccine. The vaccine employs a xenogeneic p53 gene to break immune tolerance resulting in a potent therapeutic antitumor effect against tumors expressing mutated p53. Our study assessed the therapeutic antitumor effect after immunization with DNA encoding human p53 (hp53) or mouse p53 (mp53). Mice immunized with xenogeneic full length hp53 DNA plasmid intramuscularly followed by electroporation were protected against challenge with murine colon cancer MC38 while those immunized with mp53 DNA were not. In a therapeutic model, established MC38 tumors were also well controlled by treatment with hp53 DNA therapy in tumor bearing mice compared to mp53 DNA. Mice vaccinated with hp53 DNA plasmid also exhibited an increase in mp53-specific CD8(+) T-cell precursors compared to vaccination with mp53 DNA. Antibody depletion experiments also demonstrated that CD8(+) T-cells play crucial roles in the antitumor effects. This study showed intramuscular vaccination with xenogeneic p53 DNA vaccine followed by electroporation is capable of inducing potent antitumor effects against tumors expressing mutated p53 through CD8(+) T cells.

Bonham, K., et al. (2010). “Effects of a novel arginine methyltransferase inhibitor on T-helper cell cytokine production.” FEBS J 277(9): 2096-2108. PubMed

The protein arginine methyltransferase (PRMT) family of enzymes catalyzes the transfer of methyl groups from S-adenosylmethionine to the guanidino nitrogen atom of peptidylarginine to form monomethylarginine or dimethylarginine. We created several less polar analogs of the specific PRMT inhibitor arginine methylation inhibitor-1, and one such compound was found to have improved PRMT inhibitory activity over the parent molecule. The newly identified PRMT inhibitor modulated T-helper-cell function and thus may serve as a lead for further inhibitors useful for the treatment of immune-mediated disease.

Shibasaki, Y., et al. (1997). “Massive actin polymerization induced by phosphatidylinositol-4-phosphate 5-kinase in vivo.” J Biol Chem 272(12): 7578-7581. PubMed

The Rho family GTP-binding proteins have been known to mediate extracellular signals to the actin cytoskeleton. Although several Rho interacting proteins have been found, downstream signals have yet to be determined. Many actin-binding proteins are known to be regulated by phosphatidylinositol 4,5-bisphosphate in vitro. Rho has been shown to enhance the activity of phosphatidylinositol-4-phosphate 5-kinase (PI4P5K), the phosphatidylinositol 4,5-bisphosphate synthesizing enzyme. Recently we isolated several isoforms of type I PI4P5K. Here we report that PI4P5K Ialpha induces massive actin polymerization resembling “pine needles” in COS-7 cells in vivo. When truncated from the C terminus to amino acid 308 of PI4P5K Ialpha, both kinase activity and actin polymerizing activity were lost. Although the dominant negative form of Rho, RhoN19, alone decreased actin fibers, those induced by PI4P5K were not affected by the coexpression of RhoN19. These results suggest that PI4P5K is located downstream from Rho and mediates signals for actin polymerization through its phosphatidylinositol-4-phosphate 5-kinase activity.

Zhang, J., et al. (1996). “Dynamin and beta-arrestin reveal distinct mechanisms for G protein-coupled receptor internalization.” J Biol Chem 271(31): 18302-18305. PubMed

The process of agonist-promoted internalization (sequestration) of G protein-coupled receptors (GPCRs) is intimately linked to the regulation of GPCR responsiveness. Following agonist-mediated desensitization, sequestration of GPCR is presumably associated with the dephosphorylation and recycling of functional receptors. However, the exact mechanisms responsible for GPCR sequestration, even for the prototypic beta2-adrenergic receptor (beta2AR), have remained controversial. We demonstrate here that dynamin, a GTPase that regulates the formation and internalization of clathrin-coated vesicles, is essential for the agonist-promoted sequestration of the beta2AR, suggesting that the beta2AR internalizes via the clathrin-coated vesicle-mediated endocytic pathway. In contrast, internalization of the angiotensin II type 1A receptor (AT1AR), another typical GPCR, does not require dynamin. In addition, the AT1AR internalizes independent of the function of beta-arrestin, a critical component for beta2AR cellular trafficking, but additional AT1ARs are mobilized to the dynamin-dependent pathway upon overexpression of beta-arrestin. These findings demonstrate that GPCRs can utilize distinct endocytic pathways, distinguishable by dynamin and beta-arrestin, and that beta-arrestins function as adaptor proteins specifically targeting GPCRs for dynamin-dependent endocytosis via clathrin-coated vesicles.