Recombinant Human CD19 Protein, Seafrom (CAT#: STEM-CT-0103-ZJF)

The Recombinant Human CD19 Protein manufactured by Seafrom is suitable for B-cell activation and antibody production.
B lymphocyte antigen CD19, also known as CD19 (Cluster of Differentiation 19), is a single-pass type I membrane protein containing two Ig-like C2-type (immunoglobulin-like) domains. CD19 is expressed on follicular dendritic cells and B cells. In fact, it is present on B cells from early recognizable B-lineage cells during development to B cell progenitors, but it is lost as they mature into plasma cells. It primarily acts as a co-receptor on B cells, often alongside CD21 and CD81. Upon activation, the cytoplasmic tail of CD19 becomes phosphorylated, leading to the recruitment of Src-family kinases and PI-3 kinases. Like T cells, some surface molecules form antigen receptors and complexes on B lymphocytes. Most B cell-specific CD19 phosphorylated glycoprotein is one of these molecules, along with CD21 and CD81. These surface immunoglobulin (sIg)-associated molecules facilitate signal transduction. On live B cells, anti-immunoglobulin antibodies mimic exogenous antigens, causing CD19 to bind with sIg and internalize it. The reverse process has not been confirmed, indicating that the formation of this receptor complex is antigen-induced. This molecular interaction has been chemically proven. Mutations in CD19 are associated with severe immunodeficiency syndrome characterized by reduced antibody production. CD19 has been shown to interact with CD81, CD82, complement receptor 2, and VAV2.
The lyophilized form can be stored at 4°C for 24 months, and the reconstituted liquid can be stored at -20°C for 6-12 months, avoiding repeated freeze-thaw cycles.

Expression Host: Human HEK293 cells
Source: Human
Synonyms: CD19, B4, CVID3, MGC12802
Protein Sequence: The DNA sequence encodes human CD19 (UniProtKB/Swiss-Prot: P15391.6), expressed with a His tag at the C-terminus.
Molecular Weight: Recombinant human CD19 protein contains 271 amino acids, with a predicted theoretical molecular weight of 31.8 kD.
Purity: ≥95%, confirmed by SDS-PAGE gel and high-performance liquid chromatography (HPLC) analysis.
Endotoxin: <0.1 EU/μg
Biological Activity: The monoclonal antibody against CD19 at 5μg/mL (100 μL/well) can bind to CD19 protein in a linear range of 5-100 ng/mL.
Purification Method: Chromatographic purification
Composition: Sterile PBS (pH 7.4) freeze-dried powder containing 6% mannitol.

Optimal Stability
Gmp-Grade Quality
Low Batch-to-Batch Variability
Exceptional Specificity
Robust Bioactivity
Efficient and Reliable Performance

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