| 纯度 | >95%SDS-PAGE. |
| 种属 | Human |
| 靶点 | CST4 |
| Uniprot No | P01036 |
| 内毒素 | < 0.01EU/μg |
| 表达宿主 | E.coli |
| 表达区间 | 21-141aa |
| 氨基酸序列 | MGSSHHHHHH SSGLVPRGSH MGSMSSSKEE NRIIPGGIYD ADLNDEWVQR ALHFAISEYN KATEDEYYRR PLQVLRAREQ TFGGVNYFFD VEVGRTICTK SQPNLDTCAF HEQPELQKKQ LCSFEIYEVP WEDRMSLVNS RCQEA |
| 预测分子量 | 17 kDa |
| 蛋白标签 | His tag N-Terminus |
| 缓冲液 | PBS, pH7.4, containing 0.01% SKL, 1mM DTT, 5% Trehalose and Proclin300. |
| 稳定性 & 储存条件 | Lyophilized protein should be stored at ≤ -20°C, stable for one year after receipt. Reconstituted protein solution can be stored at 2-8°C for 2-7 days. Aliquots of reconstituted samples are stable at ≤ -20°C for 3 months. |
| 复溶 | Always centrifuge tubes before opening.Do not mix by vortex or pipetting. It is not recommended to reconstitute to a concentration less than 100μg/ml. Dissolve the lyophilized protein in distilled water. Please aliquot the reconstituted solution to minimize freeze-thaw cycles. |
以下是关于CST4重组蛋白的模拟参考文献示例(仅供参考，实际文献需通过学术数据库查询)：
1. **文献名称**: "Expression and Purification of Recombinant Human CST4 in Escherichia coli for Functional Analysis"
**作者**: Li X, Wang Y, Zhang H.
**摘要**: 本研究成功构建了人源CST4基因的原核表达载体，利用大肠杆菌系统高效表达可溶性CST4重组蛋白，并通过镍柱亲和层析纯化。实验表明重组CST4能有效抑制半胱氨酸蛋白酶活性，为其在肿瘤研究中的应用奠定基础。
2. **文献名称**: "CST4 Recombinant Protein Suppresses Tumor Cell Invasion via Regulating Cathepsin B Activity"
**作者**: Chen J, Liu R, Zhou M.
**摘要**: 通过哺乳动物细胞表达系统获得CST4重组蛋白，发现其可特异性抑制肿瘤细胞中Cathepsin B的酶活性，显著降低癌细胞侵袭能力，提示CST4可能作为潜在的肿瘤转移治疗靶点。
3. **文献名称**: "Structural Characterization of Recombinant CST4 and Its Diagnostic Value in Salivary Gland Tumors"
**作者**: Gupta S, Patel T, Kumar A.
**摘要**: 采用酵母表达系统制备高纯度CST4重组蛋白，通过质谱和圆二色谱解析其结构。临床样本分析显示，CST4在唾液腺肿瘤患者唾液中的表达水平显著升高，具有早期诊断潜力。
4. **文献名称**: "Optimization of CST4 Recombinant Protein Production in Pichia pastoris and Its Antioxidant Activity"
**作者**: Zhang L, Wei F, Xu Q.
**摘要**: 研究通过毕赤酵母系统优化CST4重组蛋白的分泌表达条件，发现其在低pH环境下稳定性高。体外实验证实重组CST4具有清除自由基的能力，为开发抗氧化剂提供新思路。
**注**：以上文献信息为模拟内容，实际研究中请通过PubMed、Web of Science或CNKI等平台检索真实文献，并核对作者、期刊及摘要准确性。
CST4 (Cystatin-SN) is a member of the cystatin superfamily, a group of cysteine protease inhibitors that regulate proteolytic activity by inhibiting cathepsins and other cysteine-dependent enzymes. Encoded by the *CST4* gene in humans, it is primarily expressed in salivary glands, mucosal tissues, and bodily fluids, playing roles in innate immunity, inflammation modulation, and tissue homeostasis. As a secreted protein, CST4 contributes to mucosal defense by controlling excessive protease activity that could damage host tissues, while also influencing immune cell signaling and pathogen invasion.
Recombinant CST4 protein is produced using genetic engineering techniques, typically through expression in bacterial (e.g., *E. coli*) or mammalian cell systems. This allows large-scale production of the purified protein for research and therapeutic applications. Structurally, recombinant CST4 retains conserved cystatin domains critical for protease binding, including a signal peptide for secretion and a conserved QVVAG motif essential for enzyme inhibition. Post-translational modifications, such as glycosylation in mammalian-expressed CST4. may enhance its stability and functional specificity.
Research on recombinant CST4 has focused on its diagnostic and therapeutic potential. Elevated CST4 levels are associated with oral squamous cell carcinoma, allergic diseases, and chronic inflammatory conditions, making it a biomarker candidate. In vitro and in vivo studies suggest its utility in mitigating inflammation-driven tissue damage, modulating immune responses, and inhibiting tumor progression. Additionally, recombinant CST4 serves as a tool to study protease-inhibitor interactions and develop targeted therapies for diseases involving dysregulated proteolysis. Ongoing efforts aim to optimize its production, validate clinical applications, and explore engineered variants with enhanced bioactivity.
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