| Human Semaphorin 3C/Fc Chimera Semaphorin 3C (Sema3C, previously SemaE) is one of six Class 3 secreted semaphorins which share 40-50% aa identity among themselves. Class 3 semaphorins are potent chemorepellents that function in axon and/or vascular guidance during development, and may be upregulated in tumor progression. The 751aa human Sema3C is highly modular. It contains a 20aa signal sequence, an ~500aa N-terminal Sema domain that forms a beta-propeller structure similar to that found in integrin molecules, a cysteine knot, a furin-type cleavage site, an Ig-like domain, and a C-terminal basic domain. Covalent dimerization plus cleavage at the C-terminus are required for activity of class 3 semaphorins. Human Sema3C shares at least 95% aa identity with mouse, rat, cow and dog Sema3C, and 89% and 75% aa identity with chick and zebrafish Sema3C, respectively. Type 3 semaphorins transduce signals through transmembrane plexins, either directly, or by binding associated neuropilin receptors. Sema3C signaling is transduced by Plexin-D1 indirectly via neuropilin-1 or neuropilin-2. Sema3C is expressed in all somitic motor neurons, in lung buds, and in cardiac neural crest cells during development. Sema3C activates integrins in certain cells, so in addition to its repulsive activities, it sometimes acts as a chemoattractant. In the developing nervous system, this chemoattraction appears to complement Sema3A repulsion in adjacent cell layers. Sema3C also provides an attractive force opposing Sema6A and Sema6B to guide migration of neural crest endothelial cells to the cardiac outflow tract. Consequently, defects in aortic arch formation occur when Sema3C or Plexin-D1 genes or Sema3C-neuropilin interactions are disrupted. A DNA sequence encoding the mature human Semaphorin 3C (Gly 21-Ser 738, Q99985) with the aa substitutions RR Arg551Ala, Arg552Ala and RR Arg611Ala, Arg612Ala, was fused with the Fc region of human IgG1 (Pro100-Lys330) via a linker peptide (IEGRMD). The chimeric protein was expressed in a mouse myeloma cell line, NS0. Molecular Mass: The recombinant human Semaphorin 3C/Fc is a disulfide-linked homodimeric protein. Based on N-terminal amino acid sequencing, the recombinant human Semaphorin 3C/Fc starts at Gly 21. Each monomer has a molecular mass of approximately 107.7kD. The recombinant protein migrates as an approximately 110-120kD protein in SDS-PAGE under reducing conditions. Activity: Measured by its ability to enhance the adhesion of SVEC4-10 cells (mouse endothelial cells, ATCC: CRL-2181) to Fibronectin (Banu N. et al., FASEB J. 2006, 20(12):2150-2). Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. 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. |
