首页>
外文期刊>The biochemical journal
>The role of C-4-substituted mannose analogues in protein glycosylation. Effect of the guanosine diphosphate esters of 4-deoxy-4-fluoro-d-mannose and 4-deoxy-d-mannose on lipid-linked oligosaccharide assembly
【24h】
The role of C-4-substituted mannose analogues in protein glycosylation. Effect of the guanosine diphosphate esters of 4-deoxy-4-fluoro-d-mannose and 4-deoxy-d-mannose on lipid-linked oligosaccharide assembly
pThe effects of the guanosine diphosphate esters of 4-deoxy-4-fluoro-D-mannose (GDP-4FMan) and 4-deoxy-D-mannose (GDP-4dMan) on reactions of the dolichol pathway in chick-embryo cell microsomal membranes were investigated by studies with chick-embryo cell microsomal membranes iin vitro/i and in baby-hamster kidney (BHK) cells iin vivo/i. Each nucleotide sugar analogue inhibited lipid-linked oligosaccharide biosynthesis in a concentration-dependent manner. GDP-4FMan blocked iin vitro/i the addition of mannose to Dol-PP-(GlcNAc)2Man from GDP-Man (where Dol represents dolichol), but did not interfere with the formation of Dol-P-Man, Dol-P-Glc and Dol-PP-(GlcNAc)2. Although GDP-4FMan and Dol-P-4FMan were identified as metabolites of 4FMan in BHK cells labelled with [1-14C]4FMan, GDP-4FMan was a very poor substrate for GDP-Man: Dol-P mannosyltransferase and Dol-P-4FMan could only be synthesized iin vitro/i if the chick-embryo cell membranes were primed with Dol-P. It therefore appears that the inhibition of lipid-linked oligosaccharide formation in BHK cells treated with 4FMan [Grier & Rasmussen (1984) J. Biol. Chem. 259, 1027-1030] is due primarily to a blockage in the formation of Dol-PP-(GlcNAc)2Man2 by GDP-4FMan. In contrast, GDP-4dMan was a substrate for those mannosyltransferases that catalyse the transfer of the first five mannose residues to Dol-PP-(GlcNAc)2. In addition, GDP-4dMan was a substrate for GDP-Man: Dol-P mannosyltransferase, which catalysed the formation of Dol-P-4dMan. As a consequence of this, the formation of Dol-P-Man, Dol-P-Glc and Dol-PP-(GlcNAc)2 may be inhibited through competition for Dol-P. In BHK cells treated with 10 mM-4dMan, Dol-PP-(GlcNAc)2Man9 was the major lipid-linked oligosaccharide detected. Nearly normal extents of protein glycosylation were observed, but very little processing to complex oligosaccharides occurred, and the high-mannose structures were smaller than in untreated cells./p
展开▼
机译：> 4-脱氧-4-氟-D-甘露糖（GDP-4FMan）和4-脱氧-D-甘露糖（GDP-4dMan）的鸟苷二磷酸酯对雏鸡胚中多醇途径的反应的影响通过体外鸡胚细胞微粒体膜和体内婴儿仓鼠肾（BHK）细胞的研究，研究了细胞微粒体膜。每个核苷酸糖类似物以浓度依赖性方式抑制脂质连接的寡糖生物合成。 GDP-4FMan阻止体外从GDP-Man（其中Dol代表多醇）向Dol-PP-（GlcNAc）2Man中添加甘露糖，但不干扰Dol-P-Man的形成，Dol-P-Glc和Dol-PP-（GlcNAc）2。尽管GDP-4FMan和Dol-P-4FMan被鉴定为标记有[1-14C] 4FMan的BHK细胞中4FMan的代谢产物，但GDP-4FMan对于GDP-Man的底物非常差：Dol-P甘露糖基转移酶和Dol-P-如果用Dol-P灌注鸡胚细胞膜，则只能在体外合成4FMan。因此，似乎在用4FMan处理的BHK细胞中对脂质连接的寡糖形成的抑制作用[Grier＆amp; A. Rasmussen（1984）生物化学杂志。化学259，1027-1030]主要是由于GDP-4FMan阻止了Dol-PP-（GlcNAc）2Man2的形成。相反，GDP-4dMan是那些甘露糖基转移酶的底物，后者催化前五个甘露糖残基转移至Dol-PP-（GlcNAc）2。另外，GDP-4dMan是GDP-Man：Dol-P甘露糖基转移酶的底物，它催化Dol-P-4dMan的形成。结果，可以通过与Dol-P竞争来抑制Dol-P-Man，Dol-P-Glc和Dol-PP-（GlcNAc）2的形成。在用10 mM-4dMan处理的BHK细胞中，Dol-PP-（GlcNAc）2Man9是检测到的主要脂质连接寡糖。观察到接近正常的蛋白质糖基化程度，但是几乎没有加工成复杂的寡糖，并且高甘露糖结构比未处理的细胞要小。
展开▼
