a cell surface molecule which assembles with the antigen receptor of B lymphocytes. A critical signal transduction molecule that regulates B lymphocyte development, activation, and differentiation. Ligation increases intracellular calcium levels and decreases the threshold for antigen receptor signaling. Germinal center formation is significantly reduced in CD19-deficient mice. Note: This description may include information from UniProtKB.
Protein type: Cell surface; Membrane protein, integral
Cellular Component: external side of plasma membrane; extracellular exosome; integral component of plasma membrane; plasma membrane; protein complex
Molecular Function: phosphatidylinositol-4,5-bisphosphate 3-kinase activity; protein binding; receptor signaling protein activity
Biological Process: B cell receptor signaling pathway; cell surface receptor signaling pathway; cellular defense response; phosphatidylinositol phosphorylation; positive regulation of protein kinase B signaling; positive regulation of release of sequestered calcium ion into cytosol; regulation of complement activation; regulation of immune response