Recombinant Human Protogenin Protein, CF

Protogenin (PRTG; also Protein Shen‑Dan) is a 175 ‑ 180 kDa transmembrane (TM) member of the DEAL (DCC et al) family of proteins within the immunoglobulin superfamily (1 ‑ 5). Human Protogenin is an 1150 amino acid (aa) type I TM glycoprotein with a 35 aa signal sequence, a 914 aa extracellular domain (ECD), a 21 aa TM domain and a 180 aa cytoplasmic region. The ECD contains four Ig‑like domains (aa 36  ‑ 411) followed by five fibronectin type III domains (aa 419 ‑ 914). One potential splice variant shows a 49 aa insertion after aa 325 and deletion of aa 516 ‑ 541. Within the ECD, human Protogenin shares 93%, 95%, 97% and 88% aa sequence identity with mouse/rat, bovine/equine, canine and chick Protogenin, respectively. Protogenin is expressed in the mouse embryo neural tube before E10.5, which corresponds to day 28 in humans (4). From mid‑gastrulation to early somite stages, Protogenin expression is restricted to posterior neural plate and mesoderm and is concentrated within cell‑cell contacts (1 ‑ 3). It mediates homophilic intercellular adhesion, which slows initial epiblast cell migration, promotes ingression, and impacts somite organization (3). In neural tube epithelial cells, Protogenin acts as a receptor that binds soluble DnaJB11 (also called ERdj3, a stress‑inducible endoplasmic reticulum DnaJ homolog) and suppresses premature neuronal differentiation (4). An association between Protogenin polymorphisms and ADHD (attention deficit hyperactivity disorder) may indicate its involvement in human neuronal development (5). Protogenin is also present in the E10.5 mouse mandible and may promote tooth germ morphogenesis (6).