disease:Defects in CD19 are a cause of hypogammaglobulinemia [MIM:107265].,function:Assembles with the antigen receptor of B lymphocytes in order to decrease the threshold for antigen receptor-dependent stimulation.,online information:CD19 mutation db,PTM:Phosphorylated on serine and threonine upon DNA damage, probably by ATM or ATR. Phosphorylated on tyrosine following B-cell activation.,similarity:Contains 2 Ig-like C2-type (immunoglobulin-like) domains.,subunit:Forms a complex with CD21, CD81 and CD225 in the membrane of mature B cells. Interacts with VAV. Interacts with GRB2 and SOS when phosphorylated on Tyr-348 and/or Tyr-378. Interacts with PLCG2 when phosphorylated on Tyr-409.,
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Function:
activation of immune response, immune response-activating cell surface receptor signaling pathway, positive regulation of immune system process, immune response-activating signal transduction, immune response-regulating signal transduction, immune response-regulating cell surface receptor signaling pathway, defense response, cellular defense response, cell surface receptor linked signal transduction, positive regulation of response to stimulus, positive regulation of immune response, antigen receptor-mediated signaling pathway, B cell receptor signaling pathway,
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Cellular Localization:
Cell membrane ; Single-pass type I membrane protein . Membrane raft ; Single-pass type I membrane protein .
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Tissue Expression:
Detected on marginal zone and germinal center B cells in lymph nodes (PubMed:2463100). Detected on blood B cells (at protein level) (PubMed:2463100, PubMed:16672701).