Semaphorin 4A (Sema4A, previously semB) is a Class 4 transmembrane Semaphorin with activity in the immune and nervous systems. The 761aa human Sema4A precursor contains a 32aa signal sequence, a 651aa extracellular domain (ECD) containing sema, PSI and C2-type immunoglobulin domains, a 21aa transmembrane domain, and a 57aa cytoplasmic domain with two Ser/Thr phosphorylation sites. Human Sema4A ECD shares 87%, 87%, 86% and 85% aa identity with mouse, rat, bovine and canine Sema4A, respectively, and shares 32-37% aa identity with other human Sema4 family members. Of six reported splice variants with 723, 629, 370, 321, 236 and 220 aa, five lack the N-terminus and/or portions of the sema domain, and three lack the transmembrane and cytoplasmic domains in the C-terminus. Sema4A was first described as a molecule that enhances T cell activation and interacts with TIM-2 (T cell immunoglobulin and mucin domain-2). Mice with targeted disruption of Sema4A show defects in dendritic cell-mediated T cell priming and Th1 responses. Roles for Sema4A have also been identified in the brain, the endothelium and the eye. It mediates hippocampal neuron growth cone collapse in vitro through interaction of the sema domain with plexin-B1.6 Interaction of Sema4A with endothelial cell plexin-D1 causes opposition to the angiogenic, proliferative, chemotactic and integrin-mediated adhesive actions of VEGF. The retina of Sema4A-/- mice shows severe degeneration, and mutations of Sema4A are associated with retinitis pigmentosa and cone rod dystrophy in humans.
Source:A DNA sequence encoding the extracellular domain of human Semaphorin 4A (Gly 27-His 683; Accession #Q9H3S1) was fused to the Fc region of human IgG1 via a peptide linker. The chimeric protein was expressed in a mouse myeloma cell line, NS0.
Structure:Disulfide-linked homodimer
Molecular Weight:Calculated molecular mass of ~ 98.5kD. As a result of glycosylation, recombinant human Semaphorin 4A migrates as an approximately 105-120kD protein in SDS-PAGE under reducing conditions.
Activity:Measured by its ability to cause collapse of chick DRG neuron growth cones. The ED50 for this effect is typically 2.5-5ug/ml in the presence of 10ng/ml recombinant human b-NGF.
Storage and Stability:Lyophilized powder may be stored at -20°C. Stable for 12 months after receipt at -20°C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store 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.
仕様
Size：50ug
Source Antigen：Recombinant, NS0 cells
Grade：Purified
Purity：≥85%, as determined by SDS-PAGE under reducing conditions and visualized by silver stain. Endotoxin: ≤1EU/ug.
Form：Supplied as a lyophilized powder from PBS, pH 7.4, 0.05% Tween 20. Reconstitute with 500ul sterile PBS.
