Li E, Kornfeld S
J Biol Chem. 1978 Sep 25;253(18):6426-31.
Clone 15B cells, derived from Chinese hamster ovary cells and deficient in a specific UDP-N-acetylglucosamine:glycoprotein N-acetylglucosaminyltransferase activity, synthesize glycoproteins with altered oligosaccharide units. Glycopeptides prepared from these glycoproteins contain large quantities of a glycopeptide with the composition (Man)5(GlcNAc)2-Asn whereas parent cells have only small amounts of this glycopeptide. The structure of the glycopeptide was determined by the combination of methylation analysis, acetolysis, Smith periodate degradation, and alpha- and beta-mannosidase digestion. Its complete structure is Manalpha 1 leads to 6[Manalpha1 leads to 3]-Manalpha1 leads to 6[Manalpha 1 leads to 3]-Manbeta1 leads to 4 GlcNAcbeta1 leads to 4 GlcNAc leads to Asn-peptide. The structures of two other glycopeptides found in smaller quantities in clone 15B but not detected in the parent cells were determined and are Manalpha 1 leads to 6 [Manalpha 1 leads to 3]-Manalpha1 leads to 6Manbeta 1 leads to 4 GlcNAcbeta 1 leads to 4GlcNAc-Asn-peptide and Manalpha 1 leads to 3 Manalpha 1 leads to 6[Manalpha 1 leads to 3] Manbeta 1 leads to 4GlcNAcbeta 1 leads to 4GlcNAc-Asn-peptide. It is proposed that the (Man)5(GlcNAc)2-Asn unit is the physiologic acceptor for the particular N-acetylglucosaminyltransferase which is deficient in clone 15B cells and that this reaction is necessary for complex oligosacchari-e biosynthesis.
克隆15B细胞源自中国仓鼠卵巢细胞，缺乏特定的UDP-N-乙酰葡糖胺：糖蛋白N-乙酰葡糖胺基转移酶活性，能合成具有改变的寡糖单元的糖蛋白。从这些糖蛋白制备的糖肽含有大量组成成分为(Man)5(GlcNAc)2-Asn的糖肽，而亲代细胞中这种糖肽含量很少。通过甲基化分析、乙酰解、高碘酸-史密斯降解以及α-和β-甘露糖苷酶消化相结合的方法确定了该糖肽的结构。其完整结构为Manα1→6[Manα1→3]-Manα1→6[Manα1→3]-Manβ1→4GlcNAcβ1→4GlcNAc→Asn-肽。还确定了在克隆15B中少量存在但在亲代细胞中未检测到的另外两种糖肽的结构，分别为Manα1→6 [Manα1→3]-Manα1→6Manβ1→4GlcNAcβ1→4GlcNAc-Asn-肽和Manα1→3 Manα1→6[Manα1→3] Manβ1→4GlcNAcβ1→4GlcNAc-Asn-肽。有人提出，(Man)5(GlcNAc)2-Asn单元是克隆15B细胞中缺乏的特定N-乙酰葡糖胺基转移酶的生理受体，并且该反应对于复杂寡糖生物合成是必需的。
