Twisted gastrulation (TWSG1 or TSG) is a cysteine-rich 24 kDa glycoprotein. It is a secreted BMP binding protein that modulates BMP ligand availability in extracellular space. Human TSG shares 98% aa identity with mouse and rat TSG, and 99.5% aa identity with canine, equine, bovine and porcine TSG. Glycosylation and bioactivity of TWSG1 recombinant proteins vary markedly by cellular source. Non-glycosylated hTWSG1 made in E. coli has both reduced affinity for BMPs, as shown by surface plasmon resonance analysis, and reduced BMP inhibitory activity in a mandibular explant culture system compared to glycosylated proteins made in insect cells or mouse myeloma cells.
Recombinant human Twisted Gastrulation (TSG), produced in HEK 293 cells is a polypeptide chain containing 211 amino acids. A fully biologically active molecule, rhTSG has a molecular mass of 30~33 kDa analyzed by reducing SDS-PAGE and is obtained by chromatographic techniques at ExCell Bio.