Structure, Biosynthesis & Function of Glycoproteins

这项研究的目的是获得一个分子的了解磷酸甘露糖基 在将新合成的酸性水解酶递送到溶酶体中起作用的靶向系统。 这种细胞内蛋白质转运途径的缺陷引起严重的溶酶体贮积病。一个关键 该途径中的一步是选择性磷酸化高甘露糖聚糖上的甘露糖残基， 通过UDP-GlcNAc酸水解酶：溶酶体酶N-乙酰葡糖胺-1-磷酸转移酶 （Ptase）。该转移酶是由两个基因编码的α 2 β γ 2六聚体蛋白。我们确定α/β亚基识别酸性水解酶的共同蛋白决定簇，并介导蛋白质的降解。 酶的催化功能。γ亚基增强α/β亚基对一个亚群的活性， 酸性水解酶。具体目标1是针对确定结合的α/β亚基的结构域 酸性水解酶的蛋白质决定簇。目的2关注Man-6-P受体同源性的作用 在增强a/p对所选水解酶的活性中，γ亚基的（MRH）-结构域的作用。目标3 试图了解α/β缺陷小鼠神经变性发展的生理基础。目标4 是确定Ptase是如何定位于顺式高尔基体亚区室的。目标5是确定基本作用 GGA 2（高尔基体定位，含γ耳，ARF结合）外壳蛋白在维持新生儿 生存能力。此功能不能由GGA 1和GGA 3取代，这表明GGA未完全 多余这些研究将利用编码三种GGA的基因被破坏的小鼠。

The objective of this research proposal is to obtain a molecular understanding of the phosphomannosyl targeting system which functions In the delivery of newly synthesized acid hydrolases to lysosomes. Defects in this intracellular protein transport pathway give rise to severe lysosomal storage diseases. A key step in this pathway is the selective phosphorylation of mannose residues on the high mannose glycans of the acid hydrolases by UDP-GlcNAc: lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (Ptase). This transferase is an alpha2betagamma2 hexameric protein encoded by two genes. We established that the alpha/beta subunits recognize the common protein determinant of the acid hydrolases as well as mediating the catalytic function of the enzyme. The y subunit enhances the activity of the alpha/beta subunits toward a subset of the acid hydrolases. Specific Aim 1 is directed toward identifying the domain of the alpha/beta subunits that binds the protein determinant of the acid hydrolases. Aim 2 focuses on the role of the Man-6-P receptor homology (MRH)-domain of the gamma subunits in enhancing the activity of the a/p toward selected hydrolases. Aim 3 seeks to understand the physiologic basis for the development of neurodegeneration in alpha/beta null mice. Aim 4 is to determine how Ptase is localized to the cis-Golgi subcompartment. Aim 5 is to define the essential role of the GGA2 (for Golgi-localized, y-ear containing, ARF-binding) coat protein in maintaining neonatal viability. This function cannot be replaced by GGA1 and GGA3, establishing that the GGAs are not fully redundant. These studies will utilize mice with disruption of the genes encoding the three GGAs.