Molecular regulatory mechanism of cell surface garbohydrate expression and its pathology.

点击翻译按钮获取中文摘要

(1) Intramolecular disulfide bonds are essential for the tumor growth factor activity of TGF_<gamma>2 : Amino acid sequence analysis of TGF_<gamma>2 revealed the identity 14Kda galactoside-binding protein (galectin-1) .The TGF_<gamma>2 purified from rat tumor cells, however, showed no sugar-binding activity.To analyze the difference in each activity between TGF_<gamma>2 and galectin-1, we studied the intramolecular disulfide bonds in TGF and galectin-1 by the several methods including chemical clevage of S-S bridge, MOLD-mass spectrometry and affinity chromatography.Several lines of evidences indicated that intramolecular S-S bonds in TFG_<gamma>2 is required for TGF activity and that the lectin activity is induced by thecleavage of S-S bonds in TGF_<gamma>2, possibly as a result of the conformational change.(2) Molecular cloning, expression and specificity of GD3 synthase : We obtained the cDNA encoding GD3 synthase by the expression cloning strategy.The substrate specificy of the cloned GD3 synthase showed that this enzyme synthesizes not only GD3, but GQ1b which was believed by the other sialyltransferase, SAT5.These results suggest this enzyme play a key role in the regulation of ganglioside expression in CNS.