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).
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 seive treatment during purification process.
The FITC to protein molar ratio is 2-3.5.
Less than 1.0 EU per μg by the LAL method.
>90% as determined by SDS-PAGE.
Lyophilized from 0.22 μm filtered solution in PBS, pH7.4. Normally trehalose is added as protectant before lyophilization.
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Please see Certificate of Analysis for specific instructions.
For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.
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.
No activity loss was observed after storage at:
4-8°C for 12 months in lyophilized state;
-70°C for 3 months under sterile conditions after reconstitution.
FITC-Labeled Human CD19 (20-291), Fc Tag on SDS-PAGE under reducing (R) condition. The gel was stained overnight with Coomassie Blue. The purity of the protein is greater than 90%.
Evaluation of CAR expression
FACS Analysis of Anti-CD19 CAR Expression
293 cells were transfected with anti-CD19-scFv and RFP tag. 2e5 of the cells were stained with B. FITC-Labeled Human CD19 (20-291), Fc Tag (Cat. No. CD9-HF251, 10 µg/ml) and C. FITC-labeled protein control. A. Non-transfected 293 cells and C. FITC-labeled protein control were used as negative control. RFP was used to evaluate CAR (anti-CD19-scFv) expression and FITC was used to evaluate the binding activity of FITC-Labeled Human CD19 (20-291), Fc Tag (Cat. No. CD9-HF251) (QC tested).
B-lymphocyte antigen CD19 is also known as CD19 (Cluster of Differentiation 19), is a single-pass type I membrane protein which contains 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 earliest recognizable B-lineage cells during development to B-cell blasts but is lost on maturation to plasma cells. It primarily acts as a B cell co-receptor in conjunction with CD21 and CD81. Upon activation, the cytoplasmic tail of CD19 becomes phosphorylated, which leads to binding by Src-family kinases and recruitment of PI-3 kinase. As on T cells, several surface molecules form the antigen receptor and form a complex on B lymphocytes. The (almost) B cell-specific CD19 phosphoglycoprotein is one of these molecules. The others are CD21 and CD81. These surface immunoglobulin (sIg)-associated molecules facilitate signal transduction. On living B cells, anti-immunoglobulin antibody mimicking exogenous antigen causes CD19 to bind to sIg and internalize with it. The reverse process has not been demonstrated, suggesting that formation of this receptor complex is antigen-induced. This molecular association has been confirmed by chemical studies. Mutations in CD19 are associated with severe immunodeficiency syndromes characterized by diminished antibody production. CD19 has been shown to interact with: CD81, CD82, Complement receptor 2, and VAV2.