|Detection of Human IGSF4B/SynCAM3 by Western Blot. Western blot shows lysates of human brain (cerebellum) tissue, human brain (cortex) tissue, and human brain (hippocampus) tissue. PVDF membrane was probed with 0.2 µg/mL of Mouse Anti-Human IGSF4B/SynCAM3 Monoclonal Antibody (Catalog # MAB3678) followed by HRP-conjugated Anti-Mouse IgG Secondary Antibody (Catalog # HAF007). A specific band was detected for IGSF4B/SynCAM3 at approximately 48 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
|IGSF4B/SynCAM3 in Human Brain. IGSF4B/SynCAM3 was detected in immersion fixed paraffin-embedded sections of human brain (cerebellum) using Mouse Anti-Human IGSF4B/SynCAM3 Monoclonal Antibody (Catalog # MAB3678) at 15 µg/mL overnight at 4 °C. Before incubation with the primary antibody, tissue was subjected to heat-induced epitope retrieval using Antigen Retrieval Reagent-Basic (Catalog # CTS013). Tissue was stained using the Anti-Mouse HRP-DAB Cell & Tissue Staining Kit (brown; Catalog # CTS002) and counterstained with hematoxylin (blue). Specific staining was localized to neuronal cell membranes. View our protocol for Chromogenic IHC Staining of Paraffin-embedded Tissue Sections.|
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 (1, 2). It is a 48‑50 kDa type I transmembrane (TM) glycoprotein that is concentrated at non-junctional contact sites of neuronal axons and glial processes (2, 3). In myelinated peripheral nerve fibers, IGSF4B is concentrated at nodes of Ranvier in contact sites of Schwann cells (2). 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 (2, 4, 5). The cytoplasmic domain binds members of the MAGUK guanylate kinase subfamily, such as Dlg3, Pals2 and CASK (2). These activities are thought to play roles in adhesion and architecture at the synapse (2). Of two known splice variants, one shows an insertion of 34 aa near the mature N-terminus and probably represents a 60 kDa 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, canine and bovine sequences. The ECD of IGSF4A, B, C and D proteins share 35‑50% aa identity.