• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain.

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to inhibit BMP-10-induced alkaline phosphatase production by MC3T3?E1 mouse preosteoblast cells. The ED    ₅₀ for this effect is 0.3-1.2 μg/mL.

• Source

  Chinese Hamster Ovary cell line, CHO-derived

  Human Endoglin (Met1-Gly586) Accession # P17813	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Glu26

• Predicted Molecular Mass

  87.3 kDa (monomer)

• SDS-PAGE

  100-115 kDa, reducing conditions

Background: Endoglin/CD105

Endoglin (CD105) is a 90 kDa type I transmembrane glycoprotein of the zona pellucida (ZP) family of proteins (1?3). Endoglin and betaglycan/T beta RIII are type III receptors for TGF beta superfamily ligands, sharing 71% aa identity with within 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). Human Endoglin cDNA encodes 658 amino acids (aa) including a 25 aa signal sequence, a 561 aa extracellular domain (ECD) with an orphan domain and a two-part ZP domain, a TM domain and a 47 aa cytoplasmic domain (1?3). An isoform with a 14 aa cytoplasmic domain (S-endoglin) can oppose effects of long (L) Endoglin (6, 7). The human Endoglin ECD shares 65?72% aa identity with mouse, rat, bovine, porcine and canine Endoglin. Endoglin homodimers interact with TGF-beta 1 and TGF-beta 3 (but not TGF-beta 2), but only after binding T beta RII (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-beta 1 signals but enhance BMP7 signals in the same myoblast cell line (11). In endothelial cells, Endoglin inhibits T beta RI/ALK5, but enhances ALK1-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).

• References:

1. Gougos, A. and Letarte, M. (1990) J. Biol. Chem. 265:8361.

2. ten Dijke, P. et al. (2008) Angiogenesis 11:79.

3. Bernabeu, C. et al. (2007) J. Cell. Biochem. 102:1375.

4. Mancini, M.L. et al. (2007) Dev. Biol. 308:520.

5. Moody, J.L. et al. (2007) Stem Cells 25:2809.

6. Velasco, S. et al. (2008) J. Cell Sci. 121:913.

7. Perez-Gomez, E. et al. (2005) Oncogene 24:4450.

8. Cheifetz, S, et al. (1992) J. Biol. Chem. 267:19027.

9. Barbara, N.P. et al. (1999) J. Biol. Chem. 274:584.

10. Scharpfenecker, M. et al. (2007) J. Cell Sci. 120:964.

11. Scherner, O. et al. (2007) J. Biol. Chem. 282:13934.

12. Pece-Barbara, N. et al. (2005) J. Biol. Chem. 280:27800.

13. Arthur, H.M. et al. (2000) Dev. Biol. 217:42.

14. Lebrin, F. and C.L. Mummery (2008) Trends Cardiovasc. Med. 18:25.    

15. Venkatesha, S. et al. (2006) Nat. Med. 12:642.

• Entrez Gene IDs:

  2022 (Human); 13805 (Mouse); 497010 (Rat)

• Alternate Names:

  CD105 antigen; CD105; Endoglin; ENDOsler-Rendu-Weber syndrome 1; ENG; HHT1FLJ41744; ORW; ORW1