Spatial Organization and Stoichiometry of N-Terminal Domain-Mediated Glycosyltransferase Complexes in Golgi Membranes Determined by Fret Microscopy
Spatial Organization and Stoichiometry of N-Terminal Domain-Mediated Glycosyltransferase Complexes in Golgi Membranes Determined by Fret Microscopy
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DOI：
10.1007/s11064-012-0741-1
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发表时间：
2012-06-01
影响因子：
4.4
通讯作者：
Maccioni, Hugo J. F.
中科院分区：
文献类型：
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作者：
Ferrari, Mariana L.;Gomez, Guillermo A.;Maccioni, Hugo J. F.
糖脂糖基转移酶（GT）之间的功能联系依赖于这些蛋白质形成有组织的分子复合物的能力。这些复合物的组织、化学计量和组成可能影响它们的分选特性、亚高尔基定位，并可能决定GT在不同糖脂生物合成途径中的相对效率。在这项工作中，我们利用Forster共振能量转移显微镜在活CHO-K1细胞中研究了不同GT形成的同质复合物和异质复合物，以及它们在高尔基膜上的空间组织和分子化学计量。我们发现GalNAcT和GalT2 Ntd能够在反式高尔基网络中以1:2的摩尔比形成异质配合物，而GalT2而不是GalNAcT形成同质配合物。此外，GalNAcT/GalT2复合物表现出稳定的行为，反映在其聚集的横向组织。这些结果表明，GTs的特定拓扑结构可能在确定细胞膜中糖脂的组成方面具有功能意义。
The functional link between glycolipid glycosyltransferases (GT) relies on the ability of these proteins to form organized molecular complexes. The organization, stoichiometry and composition of these complexes may impact their sorting properties, sub-Golgi localization, and may determine relative efficiency of GT in different glycolipid biosynthetic pathways. In this work, by using Forster resonance energy transfer microscopy in live CHO-K1 cells, we investigated homo- and hetero-complex formation by different GT as well as their spatial organization and molecular stoichiometry on Golgi membranes. We find that GalNAcT and GalT2 Ntd are able to form hetero-complexes in a 1:2 molar ratio at the trans-Golgi network and that GalT2 but not GalNAcT forms homo-complexes. Also, GalNAcT/GalT2 complexes exhibit a stable behavior reflected by its clustered lateral organization. These results reveals that particular topological organization of GTs may have functional implications in determining the composition of glycolipids in cellular membranes.