Bush K T, Hendrickson B A, Nigam S K
Harvard Medical School, Department of Medicine (Renal Division), Brigham and Women's Hospital, Boston, MA.
Biochem J. 1994 Nov 1;303 ( Pt 3)(Pt 3):705-8. doi: 10.1042/bj3030705.
In order to determine whether the endoplasmic reticulum (ER) luminal FK506-binding protein, FKBP13, shares properties of ER molecular chaperones, MDCK cells were treated with either tunicamycin or Ca2+ ionophores. By Northern-blot analysis, tunicamycin resulted in a 2-fold rise in FKBP13 mRNA, whereas ionophores (A23187 and ionomycin) caused a more impressive rise in FKBP13 mRNA (up to 5-fold with ionomycin). Actinomycin D chase experiments in ionomycin-treated cells revealed no change in the half-life of FKBP13 mRNA, indicating that the increase in FKBP13 mRNA observed was not due to greater message stability. Moreover, sequencing of the 5' flanking region of the gene for murine FKBP13 revealed significant similarity to similar regions in human BiP (immunoglobulin-binding protein) and the human glucose-regulated protein grp94, including a 37 bp sequence in FKBP13 with approximately 50% identity with the unfolded protein response element of the BiP gene. Together, these data suggest a role for FKBP13 in ER protein folding.
为了确定内质网（ER）腔中的FK506结合蛋白FKBP13是否具有ER分子伴侣的特性，用衣霉素或Ca2+离子载体处理了MDCK细胞。通过Northern印迹分析，衣霉素使FKBP13 mRNA增加了2倍，而离子载体（A23187和离子霉素）使FKBP13 mRNA有更显著的增加（离子霉素处理后增加了5倍）。在离子霉素处理的细胞中进行放线菌素D追踪实验，结果显示FKBP13 mRNA的半衰期没有变化，这表明观察到的FKBP13 mRNA增加并非由于信息稳定性增强。此外，对小鼠FKBP13基因5'侧翼区域的测序显示，它与人类BiP（免疫球蛋白结合蛋白）和人类葡萄糖调节蛋白grp94的相似区域有显著相似性，包括FKBP13中一个37 bp的序列，与BiP基因的未折叠蛋白反应元件有大约50%的同源性。这些数据共同表明FKBP13在ER蛋白折叠中发挥作用。
