MD SIMULATIONS OF THE TRANSMEMBRANE REGION OF GOLGI GLYCOSYLTRANSFERASES

β-1，4-半乳糖基转移酶(β-1，4GT)是高尔基体居民 II型完整膜蛋白，具有较短的细胞质N-末端 结构域、跨膜结构域(TMD)和大的管腔C-末端 参与分泌物末端糖基化的结构域 蛋白质。该蛋白和其他类似高尔基体驻留蛋白中的TMD 在性质上很疏水，平均来说比 相应的TMD在质膜II型蛋白中，并已被 被证明对高尔基人的保留很重要。然而，准确的 其高尔基体滞留的机制仍不清楚。分子 对β-1，4GT的TMD进行了动力学模拟 来研究它的动态结构变化是否起到了作用 在其高尔基山脉的保留。假定了TMD的初始结构 是α螺旋的，模拟是周期性地进行的 用于解释低介电膜的八音分子盒 5~6成熟。β-1，4GT TMD中双突变体的模拟 (His-&gt；Leu，Cys-&>Ser)，显示缺乏高尔基体保留 指挥。初步结果表明，野生型和野生型的TMD 双突变体具有非常相似的动态行为。一位详细的MD 模拟将有助于理解结构变化 在TMD及其在高尔基体滞留中所起的作用。

The beta-1,4-galactosyltransferase (beta-1,4GT) is a Golgi resident type II integral membrane protein, with a short cytoplasmic N-terminal domain, a transmembrane domain (TMD) and a large luminal C-terminal domain which is involved in the terminal glycosylation of secreted proteins. The TMD in this and in other similar Golgi resident proteins is largely hydrophobic in character and on the average shorter than the corresponding TMD in the plasma membrane type II proteins, and has been shown to be important for Golgi retention. However, the exact mechanism of its Golgi retention still remains unknown. The molecular dynamics (MD) simulation of the TMD of beta-1,4GT has been conducted to investigate whether its dynamic structural variations play any role in its Golgi retention. The starting structure of the TMD was assumed to be alpha-helical and the simulations were conducted in a periodic box of octonal molecules to account for the low dielectric membrane medium. Simulation of a double mutant in the TMD of beta-1,4GT (His->Leu, Cys->Ser), which shows lack of Golgi retention, was also conducted. Preliminary results show that the TMD of the wild type and double mutant have very similar dynamic behavior. A detailed MD simulations will aid in the understanding of the structural variations in TMD and the role it plays in Golgi retention.