McCauliffe D P, Yang Y S, Wilson J, Sontheimer R D, Capra J D
Department of Microbiology, Dermatology, and Internal Medicine, University of Texas, Dallas 75235.
J Biol Chem. 1992 Feb 5;267(4):2557-62.
Calreticulin (CR) is a calcium binding protein that resides in the endoplasmic and sarcoplasmic reticulum and is reactive with human Ro/SS-A autoimmune sera. We have used human CR cDNA to isolate a human 6-kilobase genomic clone that contains 529 base pairs upstream of the presumed transcription start site, 9 exons, 8 introns, and several hundred base pairs 3' of a polyadenylation sequence. Analysis of the human CR promoter region reveals a number of potential regulatory sites also found in the human GRP78, GRP94, and protein disulfide isomerase promoters, including multiple Sp1 and CCAAT consensus sequences, an AP-2 recognition sequence (absent in protein disulfide isomerase), and multiple GC-rich areas. DNA footprint and gel shift analysis on the CR 5'-flanking region demonstrates an area that is bound by protein found in human but not murine nuclear extracts. This sequence is homologous with previously determined regulatory sequences of the human GRP78 and GRP94 promoters. These data indicate that CR, GRP78, GRP94, and protein disulfide isomerase may in part have similar transcriptional regulation and suggest that their gene products while structurally distinct may have similar functions or co-functions. These observations are of additional interest as all four of these genes encode acidic proteins that localize to the endoplasmic reticulum.
钙网蛋白（CR）是一种钙结合蛋白，存在于内质网和肌浆网中，可与人Ro/SS-A自身免疫血清发生反应。我们利用人CR cDNA分离出一个6千碱基的人基因组克隆，该克隆在推测的转录起始位点上游包含529个碱基对、9个外显子、8个内含子以及聚腺苷酸化序列下游几百个碱基对。对人CR启动子区域的分析揭示了一些在人GRP78、GRP94和蛋白二硫键异构酶启动子中也发现的潜在调控位点，包括多个Sp1和CCAAT共有序列、一个AP-2识别序列（蛋白二硫键异构酶中不存在）以及多个富含GC的区域。对CR 5'侧翼区域的DNA足迹和凝胶迁移分析表明，存在一个在人而非鼠核提取物中与蛋白质结合的区域。该序列与先前确定的人GRP78和GRP94启动子的调控序列同源。这些数据表明，CR、GRP78、GRP94和蛋白二硫键异构酶可能部分具有相似的转录调控，并表明它们的基因产物虽然结构不同，但可能具有相似的功能或协同功能。由于这四个基因都编码定位于内质网的酸性蛋白，这些观察结果格外引人关注。
