Endoglin is a homodimeric protein, meaning it consists of two identical subunits linked by disulfide bonds. Each subunit has a molecular weight of approximately 90 kDa due to glycosylation, although the polypeptide chain itself is around 61 kDa . The protein contains a zona pellucida (ZP) domain and an orphan domain (OD) at its N-terminal extracellular region, which is unique and does not have homology to any other known protein .
Endoglin is involved in the binding of various ligands, including TGF-β1, TGF-β3, Activin-A, BMP-2, and BMP-7. It modulates cellular responses to Bone Morphogenetic Protein (BMP)-9 and BMP-10 by interacting with the type I TGF-β signaling receptor activin receptor-like kinase (ALK)1 . This interaction is crucial for the regulation of angiogenesis, the process of new blood vessel formation, and vascular remodeling .
Mutations in the endoglin gene (ENG) are associated with hereditary hemorrhagic telangiectasia (HHT), a genetic disorder that leads to abnormal blood vessel formation. Endoglin is also implicated in preeclampsia, a pregnancy-related condition characterized by high blood pressure and damage to other organs .
The recombinant form of human endoglin is produced using the Sf9 insect cell expression system. Sf9 cells, derived from the fall armyworm Spodoptera frugiperda, are commonly used for the production of recombinant proteins due to their high expression levels and ability to perform post-translational modifications similar to those in mammalian cells .
The recombinant endoglin produced in Sf9 cells is typically fused to a C-terminal His-tag (6xHis) to facilitate purification. The protein is purified using proprietary chromatographic techniques to achieve a purity of ≥95% as determined by SDS-PAGE and HPLC .
Recombinant endoglin is used in various research applications, including studies on angiogenesis, vascular biology, and related diseases. It serves as a valuable tool for understanding the molecular mechanisms underlying these processes and for developing potential therapeutic interventions.