The molecular system of Golgi retentior of glycosyltransferases

点击翻译按钮获取中文摘要

Glycosylation of proteins and lipids is performed in the Golgi apparatus by glycosyl-transferases. They are type-II membrane proteins which consist of an N-terminal cytoplasmic region, a trans membrane region, a stem region and a c-terminal catalytic region facing to lumen of Golgi. The population of resident glycosyltransferases and sorting components must be retained in the Golgi apparatus in spite of the large flow of proteins and lipids through to other organelles in the cell. The aim of this project is to elucidate the molecular mechanisms underlying Golgi retention of glycosyltransferases.The two-hybrid system is an in vivo yeast-based system that identifies interaction between two proteins by reconstituting active transcription factor dimmers. cDNAs were prepared from human non-cancerous right hemi-colon tissues obtained as a surgical sample and a cDNA library constructed in the GAL4 activation domain vector, pPC86. We have reported that H enzyme (FUT1), Se enzyme (FUT2), Lewis type α1,3/1,4 fucosyltransferase (FUT3), α2,3 sialyl-transferases (ST3GaII and ST3GaIIV) and β1,4gaqlactosyltransferase 1 (β1,4GaIT1) express in the right hemicolon. Each gene was cloned in-frame with the GAL4 sequence encoding the DNA binding domain into pDBLeu as the bait. We carried out screening and obtained ε-COP protein, gp25L2 protein and β-tubulin as the candidate molecules interacting with FUT1 and FUT2.