Recombinant Human OCAM/NCAM2 Fc Chimera Protein, CF

OCAM (olfactory cell adhesion molecule), also known as NCAM2 (neural cell adhesion molecule 2) and RNCAM (Rb‑8 neural cell adhesion molecule) is an approximately 100 kDa type I transmembrane glycoprotein belonging to the NCAM family within the immunoglobulin superfamily (1‑5). OCAM dimerizes and participates in homophilic adhesion, but unlike NCAM1/CD56, it is not polysialic acid‑glycosylated, and does not participate in heparin sulfate binding or heterophilic adhesion (2). The 837 amino acid (aa) form of human or mouse OCAM contains a 19 aa signal sequence, a 678 aa extracellular domain (ECD) with five Ig‑like C2‑type domains and two fibronectin type III domains, a transmembrane domain and a 119 aa cytoplasmic domain (2‑4). The first two Ig‑like domains mediate homodimer formation in trans (6). In mouse, a glycosyl phosphatidylinositol‑linked form may show differential expression and function on olfactory axons (1‑3, 7). The ECD of human OCAM shares 93%, 92% and 95% aa sequence identity with mouse, rat, and bovine OCAM, respectively. Human OCAM also shares approximately 44% aa sequence identity with human NCAM1. OCAM is expressed by a subset of axons in the olfactory, vomeronasal, and retrosplenial cortex in a zone‑specific manner (1‑3, 7‑9). It is thought to be important for organization of axons and dendrites and segregation of axodendritic and dendrodendritic synapses within glomeruli (1, 7, 10, 11). Because OCAM is encoded on human chromosome 21, it is implicated in neurological abnormalities in Down Syndrome (trisomy 21) (1, 3, 4). It may also be implicated in development of autism and Alzheimer’s disease, and over‑expressed in some breast and prostate cancers (1, 5).