Recombinant Human RELT/TNFRSF19L Fc Chimera Protein, CF

RELT (Receptor Expressed in Lymphoid Tissues) is a 46 kDa (predicted) type I transmembrane glycoprotein belonging to the tumor necrosis factor receptor superfamily, designated TNFRSF19-like (TNFRSF19L) (1, 2). It is primarily expressed in hematopoietic tissues and peripheral blood leukocytes (2, 3). Human RELT cDNA encodes 430 amino acids (aa), including a 25 aa signal peptide, a 137 aa extracellular domain containing a TNF receptor cysteine-rich domain and a potential N‑linked glycosylation site, a 21 aa transmembrane domain and a 247 aa cytoplasmic region that lacks a death domain. Within the ECD, human RELT shares 78%, 75%, 75%, 78% and 72% aa sequence homology with mouse, rat, canine, porcine and bovine RELT, respectively. Among TNFRSF members, the RELT extracellular domain is most closely related to that of TROY/TNFRSF19 and OX40 (2). Neither human nor mouse RELT bind any of the ~19 TNF superfamily ligands that have been tested (1). Two related transmembrane proteins, RELL1 and RELL2, have been identified in both human and mouse (3). RELL1 and 2 can interact with and are coexpressed with RELT, and are thought to modulate its signaling (3-5). Intracellularly, RELT has been shown to bind the adaptor protein TRAF-1 and activate the NF‑ kappaB pathway, the phospholipid scramblase PLSCR1, and oxidative stress responsive proteins OSR1 (2-5). Another investigator notes association and signaling through SPAK, but not TRAF or NF kappaB (6). When overexpressed in HEK-293 cells, RELT induces p38 and JNK signaling and activates apoptosis (4-6). Immobilized RELT can also costimulate T-cell proliferation in the presence of CD3 signaling (2).