Immunoglobulin Superfamily Member 4B Recombinant Human (IGSF4B, Nectin-Like 1, Necl-1, TSLL1, CADM3,

Human IGSF4B (immunoglobulin superfamily member 4B), also called CADM3, TSLL1, Necl-1 and SynCAM-3, is a neural tissue-specific member of the nectin-like family of immunoglobulin superfamily molecules. It is a 48-50kD type I transmembrane (TM) glycoprotein , that is concentrated at non-junctional contact sites of neuronal axons and glial processes. , In myelinated peripheral nerve fibers, IGSF4B is concentrated at nodes of Ranvier in contact sites of Schwann cells. The 398 amino acid (aa) human IGSF4B contains a 24 aa signal sequence, a 306 aa extracellular domain (ECD), a 21 aa transmembrane domain and a 47 aa cytoplasmic domain. The ECD contains an N-terminal V-type Ig-like domain that is responsible for Ca ++ , -independent homophilic and heterophilic interactions with Nectin-1, Nectin-3 or Necl-2 (IGSF-4) in trans. It also contains two C2-type Ig-like domains that are responsible for Ca ++ -independent homophilic dimerization in cis that is thought to precede trans interaction. , The cytoplasmic domain binds members of the MAGUK guanylate kinase subfamily, such as Dlg3, Pals2 and CASK. These activities are thought to play roles in adhesion and architecture at , the synapse. We have also shown that IGSF4B promotes in vitro outgrowth of cortical neurons. Of two known splice variants, one shows an insertion of 34 aa near the mature N-terminus and probably represents a 60kD form. A smaller variant shows deletions of aa # 185-231, and 281-398, which includes the first C2-type Ig-like domain and the TM segment. The IGSF4B ECD is highly conserved, sharing 95-96% aa identity between human mouse, rat, dog and cow sequences. The ECD of IGSF-4A, B, C and D proteins share 35-50% aa identity. , Molecular Mass:, Based on N-terminal amino acid sequencing, the recombinant human IGSF4B protein starts at Pro 21 and has a predicted molecular mass of approximately 34.5kD. As a result of glycosylation, the recombinant monomer migrates as an approximately 38-41kD protein on a SDS-PAGE gel. The preparation may contain human IGSF4B that starts at Asn 25. , , Endotoxin Level: < 1.0 EU per 1ug 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. , Recommended Dilutions: , Immobilized rh IGSF4B (at a 3il droplet containing 50 ng) on a nitrocellulose coated microplate is sufficient to significantly enhance neurite outgrowth. , Optimal dilutions to be determined by the researcher. Hybridoma: A DNA sequence encoding the signal peptide from human CD33 joined with the extracellular domain of human IGSF4B (Pro 21-Tyr 329, Accession # Q8N126) was fused with a 6x histidine tag at the C-terminus. The chimeric protein was expressed in a mouse myeloma cell line, NS0. 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.