葡萄糖调节蛋白(GRP78)也称为结合免疫球蛋白或BiP，是内质网的常驻分子伴侣，参与蛋白质的折叠和组装，新合成的多肽穿过内质网膜的转运，钙稳态的调节和靶向错误折叠的蛋白质进行降解。GRP78还通过结合内质网腔内的N-末端结构域来调节跨膜蛋白PERK、IRE1和ATF6，防止这些信号转导子启动未折叠蛋白反应(UPR)，这是对细胞内环境变化的适应性反应，旨在恢复正常的内质网功能。
当蛋白质发生错误折叠时，蛋白质上暴露的疏水残基被GRP78结合，阻止蛋白质聚集、进一步转运和分泌。细胞内应激如葡萄糖缺乏和病毒感染可导致未折叠蛋白的快速积累。随着未折叠蛋白的积累，需要更多可用的GRP78来结合疏水区，使其与跨膜信号蛋白分离，从而启动UPR。与GRP78分离后，激活的PERK减弱一般翻译以阻止进一步的蛋白质合成，ATF6和IRE1上调内质网折叠和伴侣蛋白的产生，包括GRP78，以及通过内质网相关蛋白降解促进错误折叠蛋白降解的蛋白(ERAD)。由于UPR激活而导致的GRP78的过度表达有助于代谢性疾病、炎性疾病、神经退行性疾病和癌症的发生发展。
Enzo Life Sciences提供的Grp78/BiP ELISA试剂盒可用于未折叠蛋白反应、癌症和神经退行性疾病研究中检测正常和上调Grp78/BiP水平。该产品灵敏度高，可在2.5小时内获得检测结果。
产品信息
| 产品货号 | ADI-900-214-0001/欣博盛生物 |
| 产品名称 | Grp78/BiP ELISA kit |
| 产品规格 | 96 wells |
| 灵敏度 | 8.4ng/ml |
| 检测范围 | 1.4-4500ng/ml |
| 其他名称 | Glucose-regulated protein 78, Binding immunoglobulin protein |
| 检测时间 | 2.5 hours |
| 适用样本类型 | 细胞裂解物，血清 |
| 适用种属 | 人，小鼠，大鼠 |
| 交叉反应 | No cross-reactivity with other similar molecules (Grp94, PDI, Calreticulin) detected using this assay |
| 试剂盒组分 | Microtiter Plate, Conjugate, Antibody, Assay Buffer, Wash Buffer Concentrate, Standard, TMB Substrate, Stop Solution 2, Extraction Reagent |
标准曲线示例
ELISA与WB实验对比
图.C6细胞裂解物的Grp78/BiP的ELISA与WB相关性比较。 将裂解物连续稀释后进行ELISA和WB实验(WB使用12%Tris-甘氨酸凝胶，转移到硝化纤维素膜上，并用针对GRP78蛋白KDEL部分的单克隆抗体检测GRP78)。
GRP78诱导分析
图. 使用环孢菌素A诱导分析GRP78：分别用5μM、50μM或200μM浓度的环孢素A处理HeLa细胞5小时。孵育后，用提取试剂#2裂解处理和未处理的细胞，检测裂解物。上图数据与文献中报道的结果一致，低浓度的环孢菌素A可诱导HeLa细胞中的GRP78（Paslaru，L.等人（1994）），Enzo Grp78/BiP ELISA kit能够检测和定量GRP78天然水平的变化。
部分产品文献引用
1. ER-stress-induced secretion of circulating glucose-regulated protein 78kDa (GRP78) ameliorates pulmonary artery smooth muscle cell remodelling: M.A. Zaidi, et al.; Cell Stress Chaperones 27, 561 (2022)
2. Circulating chaperones in patients with aortic valve stenosis undergoing TAVR: impact of concomitant chronic kidney disease: A. Aksoy, et al.; Transl. Res. 223, 117 (2021), Application(s): Human Serum
3. Reduction in FSH Throughout the Menstrual Cycle After Omega-3 Fatty Acid Supplementation in Young Normal Weight but not Obese Women: J.L. Bauer, et al.; Reprod. Sci. 26, 1025 (2019), Application(s): Human pooled serum
4. Circulating GRP78 acts as a biomarker in the early diagnosis of lung cancer: F. Huang, et al.; Int. J. Clin. Exp. Pathol. 11, 5223 (2018), Application(s): ELISA using human plasma
5. Heme scavenging reduces pulmonary endoplasmic reticulum stress, fibrosis, and emphysema: S. Aggarwal, et al.; JCI Insight 3, e120694 (2018), Application(s): ELISA using human plasma
6. Secreted GRP78 activates EGFR-SRC-STAT3 signaling and confers the resistance to sorafeinib in HCC cells: R. Li, et al.; Oncotarget 8, 19354 (2017), Application(s): ELISA using serum
7. Citrullinated glucose-regulated protein 78 is an autoantigen in type 1 diabetes: D. Rondas, et al.; Diabetes 64, 573 (2015), Application(s): ELISA using culture supernatants
8. Oxidative and pro-inflammatory effects of cobalt and titanium oxide nanoparticles on aortic and venous endothelial cells: R. Alinovi, et al.; Toxicol. In Vitro 29, 426 (2015), Application(s): ELISA using cell lysates
9. Serum GRP78 as a Tumor Marker and Its Prognostic Significance in Non-Small Cell Lung Cancers: A Retrospective Study: X. Ma, et al.; Dis. Markers 2015, 814670 (2015), Application(s): ELISA using human serum
