S100 Calcium Binding Protein A13, Recombinant, Murine (S100A13)

Mouse S100A13 is an 11kD member of the S100 (soluble in 100% saturated ammonium sulfate) family of vertebrate EF-hand Ca ++ -binding proteins. It is widely expressed as a homodimer with 98 amino acid (aa) long subunits. Mouse S100A13 shares 87%, 83%, 91%, 86%, 81% and 53% aa identity with rat, human, cow, dog, opossum and chicken S100A13, respectively. Like other S100 proteins, S100A13 is small and generally acidic, but it contains a basic residue-rich sequence at the C terminus, and two EF hand motifs that bind Ca++ with differing affinities. Some S100 proteins, including S100A13, are able to bind the cell surface receptor for advanced glycation end-products (RAGE). Despite lacking a signal sequence, S100A13 plays an important role in Cu ++ -dependent export of FGF-1 (FGF acidic) and IL-1 alpha from the cell in response to stresses such as heat shock, anoxia and starvation. Binding of copper is necessary for formation of a multi-protein complex between S100A13, FGF-1 and p40 synaptotagmin-1 (syt-1). Cu ++ ions supplied by S100A13 are thought to oxidize and downregulate the activity of FGF-1 prior to export. Calcium influx may also play a similar role in FGF-1 release from neuronal cells. S100A13 is composed of four amphiphilic helices that may interact with acidic phospholipid headgroups. With FGF-1 and syt-1, S100A13 likely perturbs the membrane, which allows the S100A13 protein complex to exit the cell S100A13 has been proposed as a marker for angiogenesis in tumors and endometrium, due to its role in stress-induced export of FGF-1. Based on in house studies, S100A13 has also been found to promote neurite outgrowth from rat cortical embryonic neurons. , Molecular Mass: The non-methionyl form of recombinant mouse S100A13 contains 97 amino acid residues and has a predicted molecular mass of approximately 11kD. Endotoxin Level: < 1EU/ug of the protein as determined by the LAL method. , Biological Activity: Measured by its ability to enhance neurite outgrowth of cortical neurons from E18 rat embryos. Immobilized rmS100A13 (at a 3il droplet containing 50 ng) on a nitrocellulose coated microplate is sufficient to significantly enhance neurite outgrowth. Storage and Stability: , Lyophilized powder may be stored at -20°C. Reconstitute to nominal volume by adding sterile PBS. Aliquot and store at -20°C. Reconstituted product is stable for 1 month at 4°C and 3 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.