Independent and simultaneous translocation of two substrates by a nucleotide sugar transporter
Independent and simultaneous translocation of two substrates by a nucleotide sugar transporter
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DOI：
10.1073/pnas.0608159103
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发表时间：
2006-10-31
影响因子：
11.1
通讯作者：
Berninsone, Patricia M.
中科院分区：
文献类型：
--
作者：
Caffaro, Carolina E.;Hirschberg, Carlos B.;Berninsone, Patricia M.
核苷酸糖转运蛋白在蛋白质和脂质糖基化中起重要作用，突变可导致发育表型。我们已经表征了由秀丽隐杆线虫基因C03H15.2编码的UDP-N-乙酰葡糖胺和UDP-N-乙酰半乳糖胺的转运蛋白。令人惊讶的是，这些底物的易位以独立和同时的方式发生，既不是竞争性运输，也不是共转运。将表达C03H5.2蛋白的酿酒酵母的高尔基体囊泡与在其糖中标记有H-3和C-14的这些核苷酸糖一起孵育，表明两种底物以相同的程度进入管腔，无论它们是否单独孵育或在10倍过量的另一种核苷酸糖存在下孵育。含有C03H15.2蛋白缺失突变体的囊泡以与野生型转运蛋白相当的速率转运UDP-N-乙酰葡糖胺，而UDP-N-乙酰半乳糖胺的转运降低了85- 90%，导致底物转运的不对称损失。
Nucleotide sugar transporters play an essential role in protein and lipid glycosylation, and mutations can result in developmental phenotypes. We have characterized a transporter of UDP-N-acetylglucosamine and UDP-N-acetylgalactosamine encoded by the Caenorhabditis elegans gene C03H15.2. Surprisingly, translocation of these substrates occurs in an independent and simultaneous manner that is neither a competitive nor a symport transport. Incubations of Golgi apparatus vesicles of Saccharomyces cerevisiae expressing C03H5.2 protein with these nucleotide sugars labeled with H-3 and C-14 in their sugars showed that both substrates enter the lumen to the same extent, whether or not they are incubated alone or in the presence of a 10-fold excess of the other nucleotide sugar. Vesicles containing a deletion mutant of the C03H15.2 protein transport UDP-N-acetylglucosamine at rates comparable with that of wild-type transporter, whereas transport of UDP-N-acetylgalactosamine was decreased by 85-90%, resulting in an asymmetrical loss of substrate transport.