葡萄糖調(diào)節(jié)蛋白(GRP78)也稱為結(jié)合免疫球蛋白或BiP，是內(nèi)質(zhì)網(wǎng)的常駐分子伴侶，參與蛋白質(zhì)的折疊和組裝，新合成的多肽穿過內(nèi)質(zhì)網(wǎng)膜的轉(zhuǎn)運，鈣穩(wěn)態(tài)的調(diào)節(jié)和靶向錯誤折疊的蛋白質(zhì)進行降解。GRP78還通過結(jié)合內(nèi)質(zhì)網(wǎng)腔內(nèi)的N-末端結(jié)構(gòu)域來調(diào)節(jié)跨膜蛋白PERK、IRE1和ATF6，防止這些信號轉(zhuǎn)導子啟動未折疊蛋白反應(UPR)，這是對細胞內(nèi)環(huán)境變化的適應性反應，旨在恢復正常的內(nèi)質(zhì)網(wǎng)功能。

當?shù)鞍踪|(zhì)發(fā)生錯誤折疊時，蛋白質(zhì)上暴露的疏水殘基被GRP78結(jié)合，阻止蛋白質(zhì)聚集、進一步轉(zhuǎn)運和分泌。細胞內(nèi)應激如葡萄糖缺乏和病毒感染可導致未折疊蛋白的快速積累。隨著未折疊蛋白的積累，需要更多可用的GRP78來結(jié)合疏水區(qū)，使其與跨膜信號蛋白分離，從而啟動UPR。與GRP78分離后，激活的PERK減弱一般翻譯以阻止進一步的蛋白質(zhì)合成，ATF6和IRE1上調(diào)內(nèi)質(zhì)網(wǎng)折疊和伴侶蛋白的產(chǎn)生，包括GRP78，以及通過內(nèi)質(zhì)網(wǎng)相關蛋白降解促進錯誤折疊蛋白降解的蛋白(ERAD)。由于UPR激活而導致的GRP78的過度表達有助于代謝性疾病、炎性疾病、神經(jīng)退行性疾病和癌癥的發(fā)生發(fā)展。

Enzo Life Sciences提供的Grp78/BiP ELISA試劑盒可用于未折疊蛋白反應、癌癥和神經(jīng)退行性疾病研究中檢測正常和上調(diào)Grp78/BiP水平。該產(chǎn)品靈敏度高，可在2.5小時內(nèi)獲得檢測結(jié)果。

產(chǎn)品信息

標準曲線示例

ELISA與WB實驗對比

圖.C6細胞裂解物的Grp78/BiP的ELISA與WB相關性比較。 將裂解物連續(xù)稀釋后進行ELISA和WB實驗(WB使用12%Tris-甘氨酸凝膠，轉(zhuǎn)移到硝化纖維素膜上，并用針對GRP78蛋白KDEL部分的單克隆抗體檢測GRP78)。

GRP78誘導分析

圖. 使用環(huán)孢菌素A誘導分析GRP78：分別用5μM、50μM或200μM濃度的環(huán)孢素A處理HeLa細胞5小時。孵育后，用提取試劑#2裂解處理和未處理的細胞，檢測裂解物。上圖數(shù)據(jù)與文獻中報道的結(jié)果一致，低濃度的環(huán)孢菌素A可誘導HeLa細胞中的GRP78（Paslaru，L.等人（1994）），Enzo Grp78/BiP ELISA kit能夠檢測和定量GRP78天然水平的變化。

部分產(chǎn)品文獻引用

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

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