Transforming growth factor beta 1 (TGF-ß1) is a member of the transforming growth factor beta superfamily of cytokines. TGF-ß1 precursor contains 390 amino acids with an N-terminal signal peptide of 29 amino acids required for secretion from a cell, a 249 amino acids pro-region ( latency associated peptide or LAP), and a 112 amino acids C-terminal region that becomes the active TGF-ß1 upon activation.Both LAP and TGF-ß1 exist as homodimers in circulation, but the disulfide linked homodimers of LAP and TGF-ß1 remain non-covalently associated, forming the small latent TGF-ß1 complex (SLC, 100 kD). The large latent TGF-ß1 Complex (LLC, 235 – 260 kD) contains a third component, the latent TGF-ß binding protein (LTBP), which is linked to LAP by a single disulfide bond. The LTBP does not confer latency, but for efficient secretion of the complex to extracellular sites. Free active TGF-ß1 can be released (activated) by many factors including enzymes and low or high pH. TGF-ß1 is nearly 100% conserved across mammalian species. It has diverse biological functions in multiple cellular processes such as regulating proliferation and differentiation of various cell types. TGF-ß1 is also an important immunoregulatory cytokine, which is involved in the maintenance of self-tolerance, Th17 differentiation, and T cell homeostasis etc.It is expected that normal serum, plasma, or other biological fluid contains low concentration of free active TGF-ß1 and high concentration of Latent TGF-ß1. It is the free active form TGF-ß1 that binds TGF-ß receptor and exerts biological functions. However, it has been difficult to quantify the free active TGF-ß1 because of insufficient sensitivities of most assay products currently available on the market. It is necessary to measure both the free active form and total TGF-ß1 in biological samples to understand the TGF-ß1 functions.
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ELISA的基础是抗原或抗体的固相化及抗原或抗体的酶标记。结合在固相载体表面的抗原或抗体仍保持其免疫学活性，酶标记的抗原或抗体既保留其免疫学活性，又保留酶的活性。在测定时，受检标本（测定其中的抗体或抗原）与固相载体表面的抗原或抗体起反应。用洗涤的方法使固相载体上形成的抗原抗体复合物与液体中的其他物质分开。再加入酶标记的抗原或抗体，也通过反应而结合在固相载体上。此时固相上的酶量与标本中受检物质的量呈一定的比例。加入酶反应的底物后，底物被酶催化成为有色产物，产物的量与标本中受检物质的量直接相关，故可根据呈色的深浅进行定性或定量分析。由于酶的催化效率很高，间接地放大了免疫反应的结果，使测定方法达到很高的敏感度。
需要的仪器有：酶标仪、恒温箱、枪、枪头、烧杯、滤纸.当然有自动洗板机最好.
DAS-ELISA试剂盒中抗体有包被抗体和酶标抗体，这两种抗体是一种抗体，前者没有酶标，后者用酶进行了标记。
NCM-ELISA一般有一抗和二抗，这两种抗体不一样，前者（一抗）一般是鼠抗体或兔抗体，没有酶标，相对应的二抗一般是羊抗鼠或羊抗兔抗体，用酶进行标记。也有用马大规模备抗体的。
TDS-ELISA是三抗体ELISA，第三级的抗体是将信号级联放大。
以上三种是比较常见的，还有其他一些试剂盒，可参考免疫学的内容。
首先要什么有什么的，你得好好考虑一下。
2、看生产地址
根本没有生产地址，我们知道做实验做产品需要很多的仪器、试剂、耗材，没有人相信一间简单的屋子可以生产各种样的试剂盒。
3、看产品包装
没有任何的生产地址、联系方式等信息，这种产品有问题了连个投诉的地方都没有。
4、看公司网站
有些打着国外原装旗号，整个公司网站为英文页面，实际注册IP地址在中国。如果写着国外的地址，让你国外的朋友实地去看一下！
5、做交叉验证
拿对方提供的几个种类的试剂盒，把里面的关键组份相互替换做做实验，如果交叉严重，只能说明是一种原料生产的试剂盒贴了不同的标签。
6、看价格
价格低得离谱，却打着进口大公司原料分装，核算成本，这种低得离谱的价格是连原料都买不起的。
