Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal microenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading.||Source:|Partial recombinant protein corresponding to aa29-222 from human HLA-DPA1, fused to His-Tag at N-terminal, expressed in E. coli. ||Molecular Weight: |~26.3kD||AA Sequence:|AGAIKADHVSTYAAFVQTHRPTGEFMFEFDEDEMFYVDLDKKETVWHLEEFGQAFSFEAQGGLANIAILNNNLNTLIQRSNHTQATNDPPEVTVFPKEPVELGQPNTLICHIDKFFPPVLNVTWLCNGELVTEGVAESLFLPRTDYSFHKFHYLTFVPSAEDFYDCRVEHWGLDQPLLKHWEAQEPIQMPETTE||Storage and Stability:|May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for 6 months after receipt at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.Source: Recombinant, E. coli|Purity: ≥90% (SDS-PAGE)|Concentration: As reported|Form: Supplied as a liquid in Tris, 50% glycerol.||Important Note: This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.

USBIo全称United States BIOLOGical，位于麻省斯万普斯科特(Swampscott, MA)。全美**的抗原抗体和生化试剂供应商，目前向全球六十余个国家的科研工作者提供约50,000种抗体、抗原和生化试剂，以质量**闻名。主要产品种类包括：抗体、生化试剂、基因克隆相关产品、培养基、生长因子等细胞因子、分子生物学试剂。美国US Biological公司是生物化学和生物学试剂的专业生产商，产品服务于免疫学，分子生物学，分子遗传学，体外诊断，组织培养等科研领域。产品精确度高，质量稳定，产品数量巨大，提供70,000多种抗体、抗原和生化试剂等。

Usbio的生物化学品，抗体，重组蛋白，细胞培养基和分子生物学试剂盒几乎用于所有科学应用和环境，包括基因组研究，生物技术，药物开发和疾病诊断。USBio产品从经济实惠的研究数量到更大的批量可用于工艺开发和生产。我们的客户包括位于美国和国外的大多数*的制药和生物技术公司。

USbiological公司致力于以价值，诚信和真正的个人购买体验降低研究成本。USbiological的生物化学，抗体，重组蛋白，细胞培养基和分子生物学试剂盒几乎用于所有科学应用和环境，包括基因组研究，生物技术，药物开发和疾病诊断。产品可以从负担得起的研究数量到大批量用于工艺开发和生产。

USBio（UnitedStatesBiological，或简称USBiological）位于麻省斯万普斯科特(Swampscott,MA)。作为全美最大的抗原抗体和生化试剂供应商，USBiological目前向全球六十余个国家的科研工作者提供约150,000种抗体、抗原和生化试剂，以质量卓越闻名。主要产品种类包括：抗体、生化试剂、基因克隆相关产品、培养基、生长因子等细胞因子、分子生物学试剂。美国USBiological的产品服务于免疫学，分子生物学，分子遗传学，体外诊断，组织培养等科研领域。USBiological一直恪守“为您的研究减少成本”原则，提供高纯度、高品质的产品，并在大多数生化试剂、生物与培养基产品线上保持最高的性价比。USBiological的产品被广泛用于各种科学研究领域，包括基因组研究、生物技术、药物研发和疾病诊断等。USBiological的产品从小型科研级到生物制品大规模级规格均有提供。众多全球顶ji的生物制药和生物技术公司都在使用USBiological的高品质产品。

usbio的生化试剂，抗体，重组蛋白，细胞培养基和分子生物学试剂盒几乎用于所有科学应用和环境，包括基因组研究，生物技术，药物开发和疾病诊断。

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