| 纯度 | >90%SDS-PAGE. |
| 种属 | E.coli |
| 靶点 | lacI |
| Uniprot No | P03023 |
| 内毒素 | < 0.01EU/μg |
| 表达宿主 | E.coli |
| 表达区间 | 1-360aa |
| 氨基酸序列 | MKPVTLYDVAEYAGVSYQTVSRVVNQASHVSAKTREKVEAAMAELNYIPNRVAQQLAGKQSLLIGVATSSLALHAPSQIVAAIKSRADQLGASVVVSMVERSGVEACKAAVHNLLAQRVSGLIINYPLDDQDAIAVEAACTNVPALFLDVSDQTPINSIIFSHEDGTRLGVEHLVALGHQQIALLAGPLSSVSARLRLAGWHKYLTRNQIQPIAEREGDWSAMSGFQQTMQMLNEGIVPTAMLVANDQMALGAMRAITESGLRVGADISVVGYDDTEDSSCYIPPLTTIKQDFRLLGQTSVDRLLQLSQGQAVKGNQLLPVSLVKRKTTLAPNTQTASPRALADSLMQLARQVSRLESGQC |
| 预测分子量 | 44.7 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lacI重组蛋白的3篇经典文献及其摘要概括：
1. **"Crystal structure of the lactose operon repressor and its complexes with DNA and inducer"**
*Lewis, M. et al. (1996). Science.*
该研究解析了LacI阻遏蛋白的晶体结构，揭示了其与操纵子DNA结合及诱导物(如IPTG)结合的分子机制，阐明了变构调控的构象变化基础。
2. **"The lactose operon: A paradigm for transcriptional regulation"**
*Schleif, R. (2000). Annual Review of Biochemistry.*
综述文章，系统总结了乳糖操纵子的调控模型，重点讨论了LacI蛋白在抑制和诱导状态下的功能，及其在基因工程中作为调控工具的应用。
3. **"Genetic analysis of the lacI gene: Insights into allosteric regulation"**
*Bourgeois, S. & Jobe, A. (1972). Journal of Molecular Biology.*
通过突变实验研究了LacI蛋白的变构调控特性，鉴定了关键氨基酸残基对DNA结合和诱导物响应的作用，为理解蛋白质构效关系提供了基础数据。
(注：若需补充第四篇，可参考：Suckow, J. et al. (1996) 对LacI突变体库的功能筛选研究。)
The lacI gene, a key component of the *lac* operon in *Escherichia coli*, encodes the lactose repressor protein (LacI), a transcriptional regulator critical for lactose metabolism. Discovered in the 1960s, LacI functions as a tetrameric protein that binds to specific operator sequences (lacO) within the *lac* operon, blocking transcription in the absence of lactose. Allolactose, a lactose metabolite, acts as an inducer by binding LacI, causing conformational changes that reduce its DNA affinity and derepress the operon. This mechanism became a foundational model for gene regulation studies.
In recombinant protein systems, LacI is widely repurposed to control heterologous gene expression. Engineered plasmids often incorporate lacI alongside a modified *lac* promoter (e.g., lacUV5) or hybrid promoters (e.g., T7/lac) to enable inducible expression. In such systems, LacI constitutively represses transcription until induction by synthetic analogs like IPTG, which mimics allolactose. This tight regulation minimizes basal expression of potentially toxic proteins before induction, enhancing yield and cell viability.
LacI variants, such as LacIᵠ (overproducing mutants) or altered DNA-binding mutants, further optimize control. For example, lacIᵠ increases repressor levels, reducing leaky expression in high-copy plasmids. Additionally, LacI has been adapted for advanced applications, including gene circuits in synthetic biology and conditional knockout systems. Its modularity—compatibility with diverse promoters and hosts—underscores its utility in biotechnology.
Beyond basic research, LacI-based systems are integral to industrial protein production, drug development, and metabolic engineering. Recent studies also explore LacI-engineered switches in mammalian cells and gene therapies, highlighting its enduring versatility as a molecular tool.
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