CD19 Protein – Human CD19 recombinant protein

General Information on CD19 protein

CD19 protein also known as B-lymphocyte antigen CD19, T-cell Surface Antigen LEU-12 and CDID3 is a type I transmembrane protein coded by the gene CD19 in humans. The protein consists of a single transmembrane domain with a cytoplasmic C-terminus and an extracellular N-terminus. CD19 protein is expressed in B cell lineage but not expressed in plasma cells. This protein is also present in follicular dendritic cells. As such CD19 protein can be used a biomarker for B lymphocyte development and follicular dendritic cells. CD19 protein plays a critical role in maintaining the balance between humoral, antigen-induced response and tolerance induction.
CD19 protein acts as coreceptor for the B-cell antigen receptor complex (BCR) and functions as an adaptor protein for the recruitment of cytoplasmic signals. It decreases the threshold for activation of downstream signaling pathways involved in B-cell responses to antigens. CD protein activates signaling pathways responsible fot the activation of phosphatidylinositol 3-kinase. The latter is responsible for the mobilization of intracellular Ca2+ stores. CD19 protein is not required for early steps of B cell differentiation in the blood marrow. However, CD19 protein is required for normal B-Cell differentiation and B-cell proliferation in response to antigen challenges. This protein is also needed in the production of normal levels of high-affinity antibodies and for normal levels of serum immunoglobulins.
CD19 protein interacts with several proteins and protein complexes such as CD81 and CR2/CD21. The direct interaction of CD protein with CD81 (via the second extracellular domain) is essential for the trafficking and compartmentalization of CD19 receptor on the cell surface of activated B cells. CD19 protein, along with CR2/CD21, CD81 and IFITM1/CD225, is part of a complex in the membrane of mature B-cells. Other CD19 protein interactions include GRB2 and SOS (when phosphorylated on Tyr-348 and/or Tyr-378), PLCG2 (when phosphorylated on Tyr-409), LYN and the regulatory p85 subunit of phosphatidylinositol 3-kinase.