B-lymphocyte antigen CD19 (CD19) is also known as B-lymphocyte surface antigen B4, Differentiation antigen CD19 and T-cell surface antigen Leu-12, which is a single-pass type I membrane protein and contains two Ig-like C2-type (immunoglobulin-like) domains. CD19 forms a complex with CD21, CD81 and CD225 in the membrane of mature B cells. CD19 interacts with GRB2 and SOS when phosphorylated on Tyr-348 and/or Tyr-378. CD19 also interacts with PLCG2 when phosphorylated on Tyr-409. CD19 is an important pan B cell marker and co-stimulatory protein in humans and mice. CD19 is a hallmark differentiation antigen of the B cell lineage and positively regulates antigen receptor signal transduction in mature B cells. CD19 defines signaling thresholds for the Ag receptor as well as other cell surface receptors that regulate B lymphocyte selection, activation, and differentiation. Defects in CD19 are a cause of hypogammaglobulinemia.
Proteins and peptides
CD19, B4, CVID3, MGC12804