Tyrosine phosphorylation of B-cell adaptor for phosphoinositide 3-kinase is required for Akt activation in response to CD19 engagement.
CD19 is a coreceptor that amplifies signaling initiated by antigen cross-linking of the B-cell antigen receptor (BCR). CD19 can also signal independently of BCR coligation. This study shows that B-cell adaptor for phosphoinositide 3-kinase (BCAP), previously characterized as a substrate of the tyrosine kinases upon BCR engagement, is phosphorylated by cross-linking of CD19. Tyrosine phosphorylation of BCAP, mediated by Lyn, provides binding site(s) for phosphoinositide 3-kinase (PI3K), thereby participating in Akt activation. Thus, these results provide evidence that BCAP serves as an adaptor molecule for CD19 to activate the PI3K pathway in B cells.
Inabe
Kazunori
K
Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi, Japan.
Kurosaki
Tomohiro
T
D020816:Amino Acid Motifs; D000818:Animals; D018941:Antigens, CD19 / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D002352:Carrier Proteins / Q000378:metabolism*; D002645:Chickens; D004789:Enzyme Activation; D007152:Immunologic Capping; D046911:Macromolecular Substances; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D017464:Receptors, Complement 3d / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism
D018941:Antigens, CD19; D002352:Carrier Proteins; D046911:Macromolecular Substances; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011947:Receptors, Antigen, B-Cell; D017464:Receptors, Complement 3d; D011993:Recombinant Fusion Proteins; D019061:src-Family Kinases; C060902:lyn protein-tyrosine kinase