CD19

Functions as a coreceptor for the B-cell antigen receptor complex (BCR) on B-lymphocytes (PubMed:29523808). Decreases the threshold for activation of downstream signaling pathways and for triggering B-cell responses to antigens (PubMed:1373518, PubMed:16672701, PubMed:2463100). Activates signaling pathways that lead to the activation of phosphatidylinositol 3-kinase and the mobilization of intracellular Ca(2+) stores (PubMed:12387743, PubMed:16672701, PubMed:9317126, PubMed:9382888). Is not required for early steps during B cell differentiation in the blood marrow (PubMed:9317126). Required for normal differentiation of B-1 cells (By similarity). Required for normal B cell differentiation and proliferation in response to antigen challenges (PubMed:1373518, PubMed:2463100). Required for normal levels of serum immunoglobulins, and for production of high-affinity antibodies in response to antigen challenge (PubMed:12387743, PubMed:16672701, PubMed:9317126).

Immunodeficiency, common variable, 3

CVID3

A primary immunodeficiency characterized by antibody deficiency, hypogammaglobulinemia, recurrent bacterial infections and an inability to mount an antibody response to antigen. The defect results from a failure of B-cell differentiation and impaired secretion of immunoglobulins; the numbers of circulating B-cells is usually in the normal range, but can be low.

None

The disease is caused by variants affecting the gene represented in this entry.

Phosphorylated on tyrosine following B-cell activation (PubMed:10706702, PubMed:12387743, PubMed:7684160, PubMed:7687539). Phosphorylated on tyrosine residues by LYN (PubMed:7687428). Tyrosine residues are phosphorylated sequentially after activation of the B cell receptor. Phosphorylation of Tyr-531 is extremely rapid, followed by phosphorylation at Tyr-409. In contrast, phosphorylation of Tyr-500 appears more slowly and is more transient, returning rapidly to basal levels (By similarity).

Detected on marginal zone and germinal center B cells in lymph nodes (PubMed:2463100). Detected on blood B cells (at protein level) (PubMed:16672701, PubMed:2463100).

• Cell membrane
• Single-pass type I membrane protein
• Membrane raft
• Single-pass type I membrane protein

CD19, B-lymphocyte antigen CD19, B-lymphocyte surface antigen B4, Differentiation antigen CD19, T-cell surface antigen Leu-12

• entrezGene:930
• omim:107265
• swissprot:P15391

Proteins

Immunology & Infectious Disease

• Immuno-oncology

61128Da