| 纯度 | >90%SDS-PAGE. |
| 种属 | E.coli |
| 靶点 | lacY |
| Uniprot No | P02920 |
| 内毒素 | < 0.01EU/μg |
| 表达宿主 | E.coli |
| 表达区间 | 1-250aa |
| 氨基酸序列 | MYYLKNTNFWMFGLFFFFYFFIMGAYFPFFPIWLHDINHISKSDTGIIFAAISLFSLLFQPLFGLLSDKLGLRKYLLWIITGMLVMFAPFFIFIFGPLLQYNILVGSIVGGIYLGFCFNAGAPAVEAFIEKVSRRSNFEFGRARMFGCVGWALCASIVGIMFTINNQFVFWLGSGCALILAVLLFFAKTDAPSSATVANAVGANHSAFSLKLALELFRQPKLWFLSLYVIGVSCTYDVFDQQFANFFTSF |
| 预测分子量 | 34.4 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. |
1. **"Structure and mechanism of the lactose permease of Escherichia coli"**
- **作者**: Abramson, J. et al.
- **摘要**: 通过X射线晶体学解析了lacY蛋白的三维结构，揭示了其底物结合位点及质子梯度驱动的乳糖转运机制，为理解膜转运蛋白构象变化提供了关键依据。
2. **"The lactose permease of Escherichia coli: A paradigm for membrane transport proteins"**
- **作者**: Kaback, H.R. et al.
- **摘要**: 综述了lacY重组蛋白的功能研究进展，包括其利用重组技术表达、纯化及体外重构实验，阐明了其作为质子/乳糖共转运体的分子机制。
3. **"Site-directed alkylation studies of lacY reveal conformational changes upon substrate binding"**
- **作者**: Smirnova, I. et al.
- **摘要**: 通过定点突变和化学修饰技术，结合重组lacY蛋白的功能分析，证明了底物结合诱导的构象动态变化，揭示了转运循环中的关键中间态。
4. **"Directed evolution of a recombinant lactose permease for improved stability and activity"**
- **作者**: Guan, L. & Kaback, H.R.
- **摘要**: 利用定向进化技术优化重组lacY蛋白的稳定性和转运活性，筛选出多个关键突变体，为工业应用中的膜蛋白工程改造提供了范例。
The *lacY* gene-encoded lactose permease, a key component of the *lac* operon in *Escherichia coli*, is a well-studied secondary transporter responsible for the proton-coupled symport of β-galactosides, including lactose. Discovered in the 1960s, LacY became a model system for understanding membrane transport mechanisms. As a member of the Major Facilitator Superfamily (MFS), it utilizes the proton motive force to drive substrate uptake against concentration gradients, linking cellular metabolism to nutrient acquisition.
Structurally, LacY is a 12-transmembrane-helix bundle protein with a central substrate-binding site. Its alternating access mechanism—conformational shifts between inward- and outward-facing states—was proposed by Peter Mitchell and later validated through biochemical and biophysical studies. The 2003 X-ray crystallography breakthrough by Kaback and colleagues revealed atomic-level details of its architecture, confirming earlier predictions about helix orientation and residue involvement in substrate/proton coupling.
Recombinant LacY production, achieved through heterologous expression in systems like *E. coli* or yeast, enables controlled studies of its structure-function relationships. Engineered variants (e.g., Cys-less mutants for site-directed spin labeling) have facilitated advanced techniques like electron paramagnetic resonance (EPR) spectroscopy, providing dynamic insights into transport cycles.
LacY’s simplicity and robustness make it a cornerstone for membrane protein research, informing drug design (e.g., antibiotic transporters) and synthetic biology applications. Its study has bridged gaps between genetics, biochemistry, and structural biology, exemplifying how bacterial transporters can illuminate universal principles of cellular transport. Ongoing work explores its engineering potential for biosensors or bioenergy systems, maintaining its relevance in modern biotechnology.
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