Yeast carboxypeptidase Y requires glycosylation for efficient intracellular transport, but not for vacuolar sorting, in vivo stability, or activity.
Yeast carboxypeptidase Y requires glycosylation for efficient intracellular transport, but not for vacuolar sorting, in vivo stability, or activity.
复制标题
酵母羧肽酶 Y 需要糖基化才能实现有效的细胞内转运，但不需要糖基化来实现液泡分选、体内稳定性或活性。
DOI：
10.1111/j.1432-1033.1991.tb15959.x
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Kielland-Brandt,MC
中科院分区：
文献类型：
--
作者：
Winther,JR;Stevens,TH;Kielland-Brandt,MC
通过定点诱变去除充当 N 连接糖基化信号的序列，研究了酵母液泡酶羧肽酶 Y (CPY) 碳水化合物侧链的功能。对突变体的酶活性和细胞内分选进行了分析，并研究了其体内外稳定性。研究发现，碳水化合物对于 CPY 的准确液泡靶向并不重要，但未糖基化的 CPY 通过分泌途径运输至液泡的速率降低。衣霉素可抑制天冬酰胺连接的糖基化的形成，在 23°C 下对 CPY 的转运具有类似的作用。然而，N-连接碳水化合物的缺乏通常会产生更显着的结果，即在升高的温度（37°C）下完全阻断 CPY 的运输。在没有衣霉素的情况下，未糖基化的突变体 CPY 对于运输不具有温度敏感性。对四个位置中每个位置含有单个糖基残基的突变酶的分析表明，位置 87 的残基对于转运特别重要。完全未糖基化的酶的胞内稳定性没有降低，并且在体外该种的热灭活率没有增加。
Functions of the carbohydrate side chains of the yeast vacuolar enzyme carboxypeptidase Y (CPY) were investigated by removal, through site‐directed mutagenesis, of the sequences which act as signals for N‐linked glycosylation. The mutant forms of the enzyme were analysed with respect to activity and intracellular sorting, and the stabilitiesin vivoandin vitrowere studied. It was found that carbohydrate was not important for accurate vacuolar targeting of CPY, but that the rate of transport of the unglycosylated CPY through the secretory pathway to the vacuole was reduced. Tunicamycin, which inhibits the formation of asparagine‐linked glycosylation, had a similar effect on the transport of CPY at 23°C. However, the absence of N‐linked carbohydrate in general had the more dramatic result of blocking the transport of CPY altogether at an increased temperature (37°C). The unglycosylated mutant CPY was not temperature sensitive for transport in the absence of tunicamycin. Analysis of mutant enzymes containing a single glycosyl residue at each of the four positions showed that the residue at position 87 was particularly important for transport. There was no decrease in the intracellular stability of the completely unglycosylated enzyme, andin vitrothe rate of heat inactivation of this species was not increased.