RP2-Serpin-B7 is a polyclonal antibody made to the serine proteinase inhibitor megsin. The antibody is made to a synthetic peptide based on the reactive center loop area of human serpin-B7. The antibody has been peptide-affinity purified, concentrated to 1.0 mg/ml, with the addition of 0.05% sodium azide as preservative and 50% glycerol as cryoprotectant.
Serpin-B7, also known as megsin and TP55 (thrombopoesis Protein 55 kDa) is a serine proteinase inhibitor of the ovalbumin-like B clade of serpins. Serpin-B7 was first discovered in a search for agents responsible for thrombopoiesis, and maturation of megakaryocytes. TP55 was identified as a protein that increased acetylcholine esterase stimulation from bone barrow progenitor cells, and injection of TP55 in mice induced a 40% increase in platelets compared to controls. Shortly thereafter, in a search for kidney-specific genes, serpin-B7 was described as a protein specific to mesangial cells, and was named megsin to indicate the tissue specificity of the protein. Serpin-B7 message was found to be elevated in diabetic nepropathy and in IgA nepropathy, and overexpression of megsin in transgenic mice led to hyperproliferation of mesangial cells, glomerular lesions, and immune complex deposition. The megsin overexpression mouse is thought of as a model for diabetic nepropathy., and a polymorphism in megsin in the Chinese population is thought to confer susceptibility to IgA nepropathy. Most of the work on serpin-B7 has been in the kidney, since early publications indicated that the protein was specific to the kidney, but the human epidermoid carcinoma cell line A431 also produces serpin-B7, as do many other human cell lines. Little is known abut the serine proteinase capacity of serpin-B7. The initial publication showed that some serine protease activity was inhibited, but did not identify the specificity. Most of the serpins (SERine Proteinase Inhibitors) are serine proteinase inhibitors; although not all serine proteinase inhibitors are serpins, and visa versa. The overall structural shape of the B clade of serpins most resembles ovalbumin, which is not considered to be a serine proteinase inhibitor. The serpins share a reactive center loop motif: a substrate bait loop which, when cleaved, confers a remarkable molecular shift in the serpin molecule, and traps the enzyme. This mousetrap method works because the uncleaved serpin molecule is in tension, and cleaving the loop allows a more energetically favorable state to exist. The cleavage site in serpin-B7 is thought to be Lys347-Gln348 of the 380 amino acid sequence. The original sequence described was 380 amino acids in length, with predicted mass of 42.9 kDa and pI of 6.35. A recommended starting concentration for Western blots is 1:1,000 when using colorimetric substrates such as BCIP/NBT, and 1:5,000 for chemiluminescent substrates. Higher concentrations of antibody may be needed for samples from more distantly related species FOR RESEARCH USE ONLY; NOT FOR USE IN HUMANS.
The undiluted antibody solution is stable for approximately 12 at -20C.