MECHANISM OF ACTION OF ACETOACETATE DECARBOXYLASE

膜和分泌的糖蛋白的运输是由 通过“质量控制”机制，调解保留和 错误折叠蛋白在内质网中的降解 (呃)。涉及的分子是钙调蛋白和钙调素，它们 特异性地结合到糖基化的非还原末端 加工前的高甘露糖多糖。对于寡聚蛋白， (IGM五聚体和六聚体)，另一套规则似乎 控制它们的运输，这样没有达到 保留了合适的四元结构。中的序列 ~t的C末端，蛋白质控制SIGM的分选、保留和 降解，当保守的Cys575发生大量突变时 单体被分泌出来。该末端片段具有N-连接的糖链 在Gln663，它在所有被研究的物种中都是保守的；当这个 残留物发生突变，聚合反应再次被废除。因此，我们 对这种特定糖链的详细结构很感兴趣 CHO加工对聚合的一般影响。初始工作 已经开始建立分析限制条件， 分析N-连接多聚糖的敏感性和总体可行性 从免疫球蛋白(Ig A、Ig G、Ig D)中释放。这些材料 已经有了更大数量的产品，预计会有更多的多糖 为后续的免疫球蛋白分离部分研究提供了一个模型。 内切糖苷酶的释放效率(包括 几种洗涤剂)，甲基化后的提取，以及总体 方法的重现性。在这项初步研究中，我们应用 利用电喷雾描绘完整的多糖分布的方法学 电离-质谱仪(ESI-MS)，并进一步探讨这些 结构通过碰撞诱导解离(CID)。不存在 层析分离和发散检测技术避免了 样品不成比例。所有样本都进行了分析，只有主要样本 用CID对离子进行了详细的分析。

The transport of membrane and secreted glycoproteins is governed by "quality control" mechanisms that mediate the retention and degradation of improperly folded proteins in theendoplasmic reticulum (ER). The molecules involved are calretuculin and calnexin, which specifically bind to the non-reducing terminus of the glucosylated high mannose glycan previous to processing. For oligomeric proteins, (IgM pentamers and hexamers), an additional set of rules appears to govern their transport, such that proteins that have not achieved the proper quaternary structure are retained. Sequences within the C-terminus of the ~t, protein control sIgM sorting, retention, and degradation and when a conserved Cys575 is mutated large amounts of the monomer are secreted. This terminal piece has an N-linked glycan at Gln663,'which is conserved in all species examined; when this residue is mutated polymerization is again abrogated. Thus, we areinterested in the detailed structure of this specific glycan and the general effect of CHO processing on polymerization. Initial work has been undertaken to establish the analytical constraints, sensitivity, and overall feasibility of profiling N-linked glycans released from the immunoglobulins (IgA, IgG, IgD). These materials have been available in larger amounts and the glycans anticipated provide a model for subsequent studies with isolated fractions of Igm. Efficiency of release with endoglycosidases (including studies with several detergents), extraction after methylation, and the overall reproducibility of the method. In this preliminary study, we apply methodology to profile intact glycan distributions using electrospray ionization-mass spectrometry (ESI MS), and further probe these structures by collision-induced dissociation (CID). The absence of chromatographic separations and divergent detecting techniques avoids sample disproportionation. All samples have been profiled, only major ions have been analyzed in detail by CID.