CD105, aa1-578, Recombinant, Rat, Fc Chimera (Endoglin, ENG, END)

Endoglin (CD105) is a 90kD type I transmembrane glycoprotein of the zona pellucida (ZP) family of proteins (1-3). Endoglin and betaglycan/TBRIII are type III receptors for TGF-B superfamily ligands, sharing 71% aa identity with the transmembrane (TM) and cytoplasmic domains. Endoglin is highly expressed on proliferating vascular endothelial cells, chondrocytes, and syncytiotrophoblasts of term placenta, with lower amounts on hematopoietic, mesenchymal and neural crest stem cells, activated monocytes, and lymphoid and myeloid leukemic cells (2-5). Rat Endoglin cDNA encodes 650aa including a 25aa signal sequence, a 553aa extracellular domain (ECD) with an orphan domain and a two-part ZP domain, a TM domain and a 51aa cytoplasmic domain (1-3). In human and mouse, an isoform with a 14aa cytoplasmic domain (S-endoglin) can oppose effects of long (L) Endoglin (6). In rat, a potential isoform with a 100aa cytoplasmic tail (49aa inserted after 610aa) diverges at the same aa as S-endoglin (7). The rat Endoglin ECD shares 84%, 70%, 68%, 64%, and 62% aa identity with mouse, human, canine, porcine, and bovine Endoglin, respectively. Endoglin homodimers interact with TGF-B1 and TGF-B3 (but not TGF-B2), but only after binding TBRII (8). Similarly, they interact with activin-A and BMP-7 via activin type IIA or B receptors, and with BMP-2 via BMPR-1A/ALK-3 or BMPR-1B/ALK-6 (9). BMP-9, however, is reported to bind Endoglin directly (10). Endoglin modifies ligand-induced signaling in multiple ways. For example, expression of Endoglin can inhibit TGF-B1 signals but enhance BMP7 signals in the same myoblast cell line (11). In endothelial cells, Endoglin inhibits TBRI/ALK-5, but enhances ALK-1-mediated activation (12). Deletion of mouse Endoglin causes lethal vascular and cardiovascular defects, and human Endoglin haploinsufficiency can cause the vascular disorder, hereditary hemorrhagic telangiectasia type I (13, 14). These abnormalities confirm the essential function of Endoglin in differentiation of smooth muscle, angiogenesis, and neovascularization (2-4, 12-14). In preeclampsia of pregnancy, high levels of proteolytically generated soluble Endoglin and VEGF R1 (sFLT1), along with low placental growth factor (PlGF), are pathogenic due to antiangiogenic activity (15). Source: Recombinant corresponding to aa1-578 from rat CD105 Fc Chimera at N-terminal and C-terminal expressed in myeloma cell line, NSO. Molecular Weight: ~87kD, Endotoxin Level: <1EU/1ug (LAL), Biological Activity: Measured by its binding ability in a functional ELISA. When recombinant rat Endoglin Fc Chimera is immobilized at 2ug/ml (100ul/well), the concentration of recombinant mouse TGF-B RI Fc Chimera that produces 50% of the optimal binding response is found to be ~0.25-1.25ug/ml. Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 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.