人CD19蛋白, Fc Tag

FITC-Labeled Human CD19 (20-291) Protein, Fc Tag

分子别名（Synonym）

CD19,B4,CVID3,MGC12802

表达区间及表达系统（Source）

FITC-Labeled Human CD19 (20-291), Fc Tag (Cat. No. CD9-HF251) is expressed from human HEK293 cells. It contains AA Pro 20 - Lys 291 (Accession # P15391-1). It is the FITC labeled form of Human CD19 (20-291), Fc Tag (Cat. No. CD9-H5259).

Predicted N-terminus: Pro 20

蛋白结构（Molecular Characterization）

This protein carries a human IgG1 Fc tag at the C-terminus.

The protein has a calculated MW of 56.56 kDa. The protein migrates as 70 kDa and 150 kDa under reducing (R) condition (SDS-PAGE) due to glycosylation.

偶联（Conjugate）

FITC

Excitation source: 488 nm spectral line, argon-ion laser

Excitation Wavelength: 488 nm

Emission Wavelength: 535 nm

标记（Labeling）

The primary amines in the side chains of lysine residues and the N-terminus of the protein are conjugated with FITC using standard chemical labeling method. The residual FITC is removed by molecular sieve treatment during purification process.

蛋白标记度（Protein Ratio）

The FITC to protein molar ratio is 2-5.

纯度（Purity）

>90% as determined by SDS-PAGE.

制剂（Formulation）

Lyophilized from 0.22 μm filtered solution in PBS, pH7.4 with trehalose as protectant.

Contact us for customized product form or formulation.

重构方法（Reconstitution）

Please see Certificate of Analysis for specific instructions.

For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.

存储（Storage）

For long term storage, the product should be stored at lyophilized state at -20°C or lower.

Please protect from light and avoid repeated freeze-thaw cycles.

This product is stable after storage at:

-20°C to -70°C for 12 months in lyophilized state;

-70°C for 3 months under sterile conditions after reconstitution.

背景介绍

B淋巴细胞抗原CD19（亦称CD19或分化簇19）是一种单次跨膜I型膜蛋白，其胞外区含有两个免疫球蛋白样C2型结构域。该蛋白表达于滤泡树突细胞及B细胞表面，在B细胞发育全程——从最早可识别的B系祖细胞至B母细胞阶段持续存在，但在成熟为浆细胞时消失。CD19主要作为B细胞共受体，与CD21及CD81协同发挥作用。

当B细胞激活时，CD19胞质尾部发生磷酸化，进而招募Src家族激酶并结合PI3激酶。与T细胞类似，B淋巴细胞表面多个分子共同构成抗原受体复合物。CD19作为（近乎）B细胞特异性的磷酸化糖蛋白，与CD21、CD81共同组成该复合物。这些表面免疫球蛋白（sIg）关联分子协同介导信号转导。

在活体B细胞中，模拟外源抗原的抗免疫球蛋白抗体会引发CD19与sIg结合并随之发生内化。逆向过程尚未被证实，表明该受体复合物的形成由抗原诱导。此分子互作机制已通过化学研究获得验证。CD19基因突变可导致以抗体生成缺陷为特征的重度免疫缺陷综合征。研究证实CD19可与下列分子相互作用：CD81、CD82、补体受体2及VAV2。