多肽:N-乙酰氨基半乳糖转移酶2在SGC7901细胞中同时定位于高尔基体顺面囊和反面囊

摘要

多肽:N.乙酰氨基半乳糖转移酶(ppGalNAcT)在高尔基体中催化粘蛋白型O-糖基化的第一步.首先进行了人ppGalNAcT2多克隆抗体的制备和鉴定,进一步通过对分离的亚细胞结构进行蛋白质印迹分析,免疫细胞化学后共聚焦显微镜观察此抗体和两个高尔基体标记GS28(顺面高尔基体的分子标志)和TGN38(反面高尔基体的分子标志)来研究ppGalNAcT2在SGC7901细胞株中的亚细胞定位.结果表明:约有60%的ppGalNAcT2信号和Gs28共定位,大约36%的ppGalNAcT2信号和TGN38共定位.约有34%的TGN38和ppGalNAcT2信号重叠,而约38%的反面高尔基体标志和ppGalNAcT2重叠.结论是:在SGC7901中,ppGalNAcT2同时定位于高尔基体顺面囊和反面囊中,实验证实了在高尔基体中进行粘蛋白型O-糖基化的起始反应.%Uridine diphosphate (UDP)-GalNAc : polypeptide N-acetylgalactosaminyltransfemse (ppGalNAcT) catalyzes the initial step in mucin type O-glycosylation in the Golgi apparatus. Here generation and characterization of a polyclonal antibody to human ppGalNAcT2 were described. The subcellular location of ppGalNAeT2 in SGC7901 cell line was investigated using Western blot analysis of fractionated cell extracts and confocal microscopy with this antibody and two Golgi markers: Golgi SNARE (soluble N-ethylmalemide-sensifive factor attachment protein receptor) of 28 ku (GS28) and trans-Golgi network (TGN) 38, markers for the c/s- and trans-Golgi apparatus, respectively. Morphometric analyses indicated that ～60% of the ppGalNAcT2 signal colocalized with the GS28, while～36% of the c/s-Golgi marker colocalized with the ppGalNAeT2. Approximately 34% of the ppGalNAcT2 signal colocalized with the TGN38, whereas 38% of the trans-Golgi marker colocalized with the ppGalNAcT2. The results provide unequivocal evidence for the location ofppGalNAcT2 within the Golgi apparatus, and further highlight the importance of this organelle in the initiation of O-linked glycosylation.