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CD19 is a coreceptor that amplifies signaling by membrane immunoglobulin (mIg) to promote responses of the B lymphocyte to T-dependent antigens. Vav is a guanine nucleotide exchange factor for the Rho, Rac, Cdc42 family of small GTPases. We found that coligating mIg and CD19 causes a synergistic increase in the tyrosine phosphorylation of CD19. Phosphorylated tyrosine-391 of CD19 binds Vav to mediate a sustained increase in intracellular Ca2+ concentration. This response correlates with activation by the CD19-Vav complex of phosphatidylinositol 4-phosphate 5-kinase for the synthesis of phosphatidylinositol 4,5-bisphosphate. Interaction of CD19 with Vav also mediates the synergistic activation of the mitogen-activated protein kinase JNK. Therefore, CD19 is a membrane adaptor protein that recruits Vav for the activation of lipid and protein kinases.

Type

Journal article

Journal

Immunity

Publication Date

05/1998

Volume

8

Pages

635 - 645

Keywords

Animals, Antigens, CD19, B-Lymphocytes, Calcium, Cell Cycle Proteins, Cells, Cultured, Enzyme Activation, Guanine Nucleotide Exchange Factors, Humans, JNK Mitogen-Activated Protein Kinases, MAP Kinase Kinase 4, Mice, Mitogen-Activated Protein Kinase Kinases, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor), Protein Binding, Protein Kinases, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-vav, Rats, Tyrosine