EXPRESSION OF BETA 1-4 GALACTOSYLTRANSFERASE IN GROWING 3TC CELLS

β(1-4)半乳糖基转移酶(GT)定位于 糖蛋白被半乳糖化的高尔基体。这种酶也被 聚集在细胞表面，在那里它充当细胞黏附分子， 与末端N-乙酰氨基葡萄糖结合介导细胞间黏附 乳糖胺聚糖底物上的残留物，有桥接细胞 共同作用，并作为层粘连蛋白长臂的高亲和力受体。这个 细胞表面和高尔基转移酶似乎受到不同的调控， 前者是由异丙肾上腺素等β-肾上腺素能激动剂诱导的，没有 在某些疾病分化时影响高尔基转移酶 细胞类型是高尔基转移酶的增加，而不影响 细胞表面转移酶。GT可能参与的细胞表面 生长由于其效应分子α-乳清蛋白阻止生长 β肾上腺素能激动剂异丙肾上腺素诱导的细胞。在当前 研究我们正在研究GT在几种细胞系和 该酶在高尔基体、细胞表面、激素中的分布 参与调节这两种形式的酶和 它们在细胞周期中表达的时间。我们的结果表明 在瑞士小鼠3T3细胞中，GT在DNA复制之前表达，并且 然后下调了监管。

Beta (1-4) galactosyltransferase enzyme (GT) is localized in the trans Golgi where glycoproteins get galactosylated. This enzyme has also been gound at the cell surface where it acts as cell-adhesion molecule, mediating intercellular adhesion by binding to terminal N-acetylglucosamine residues on lactosaminoglycans substrates, there by bridging cells together, and as a high affinity receptor for the laminin long arm. The cell surface and Golgi transferase seem to be differentially regulated, the former is induced by beta-adrenergic agonist like isoproterenol without effecting the Golgi transferase while as upon differentiation of certain cell types it is the Golgi transferase that increases without effecting the cell surface transferase. The cell surface GT is possibly involved in growth since its effector molecule alpha-lactalbumin blocks the growth of cells induced by beta-adrenergic agonists isoproterenol. In the current studies we are investigating the expression of GT in several cell lines and the distribution of this enzyme in Golgi and cell surface, hormones involved in the regulation of expression of the two forms of the enzyme and the time when they are expressed during cell-cycle. Our results indicate that in Swiss mouse 3T3 cells GT is expressed prior to DNA replication and then down-regulated.