Calnexin and BiP interact with acid phosphatase independently of glucose trimming and reglucosylation in Schizosaccharomyces pombe
Calnexin and BiP interact with acid phosphatase independently of glucose trimming and reglucosylation in Schizosaccharomyces pombe
复制标题
DOI：
10.1021/bi981785c
复制
发表时间：
1998-12-08
期刊：
影响因子：
2.9
通讯作者：
Rokeach, LA
中科院分区：
文献类型：
--
作者：
Jannatipour, M;Callejo, M;Rokeach, LA
新合成的糖蛋白与ER分子伴侣钙连接蛋白和免疫球蛋白结合蛋白（BiP）的关联已在多种高等真核生物中得到充分证实。在这里，我们报告Cnx 1 p，钙连接蛋白同源裂殖酵母，协会与新合成的分泌糖蛋白酸性磷酸酶的分子。与哺乳动物钙连接蛋白的配体结合不同，酸性磷酸酶通过UDP-葡萄糖：糖蛋白葡萄糖基转移酶的葡萄糖修剪和再葡萄糖基化被证明是其与Cnx 1 p的结合所必需的。因此，尽管Cnx 1 p对于S.在粟酒裂殖酵母的存活率方面，葡萄糖修剪和再葡萄糖基化循环似乎不是分裂酵母中蛋白质折叠所需的。核心糖基化酸性磷酸酶与Cnx 1 p的协会暴露后的细胞热休克或DTT被证明是可逆的。然而，在用核心糖基化抑制剂衣霉素处理后，Cnx 1 p与非糖基化酸性磷酸酶稳定相关。BiP被发现与Cnx 1 p共沉淀，在正常和应激条件下，和以下抑制蛋白质合成放线菌酮。我们假设，Cnx 1 p和BiP是一个复杂的一部分，参与核心糖基化修剪配体和非糖基化蛋白质的折叠。
The association of newly synthesized glycoproteins with the ER molecular chaperones calnexin and immunoglobulin binding protein (BiP) has been well documented in a variety of higher eukaryotes. Here we report that Cnx1p, the calnexin homologue in Schizosaccharomyces pombe, associates with newly synthesized molecules of the secreted glycoprotein acid phosphatase. Unlike ligand binding to mammalian calnexin, glucose trimming and reglucosylation of acid phosphatase by UDP-Glc:glycoprotein glucosyltransferase were shown to be dispensable for its binding to Cnx1p. Thus, despite the essentiality of Cnx1p for S. pombe viability, the glucose trimming and reglucosylation cycle does not appear to be required for protein folding in the fission yeast. The association of core-glycosylated acid phosphatase with Cnx1p after exposure of cells to heat shock or to DTT was shown to be reversible. However, Cnx1p stably associated with unglycosylated acid phosphatase after treatment with the core-glycosylation inhibitor tunicamycin. BiP was found to coprecipitate with Cnx1p, under normal and stress conditions, and following inhibition of protein synthesis by cycloheximide. We postulate that Cnx1p and BiP are part of a complex that is involved in the folding of both core-glycosylated trimmed ligands and unglycosylated proteins.