CD19 of B cells as a surrogate kinase insert region to bind phosphatidylinositol 3-kinase.
Antigen receptors on B and T lymphocytes transduce signals by activating nonreceptor protein tyrosine kinases (PTKs). A family of receptor PTKs contains kinase insert regions with the sequence tyrosine-X-X-methionine (where X is any amino acid) that when phosphorylated mediate the binding and activation of phosphatidylinositol 3-kinase (PI 3-kinase). The CD19 membrane protein of B cells enhances activation through membrane immunoglobulin M (mIgM) and was found to contain a functional analog of the kinase insert region. Ligation of mIgM induced phosphorylation of CD19 and association with PI 3-kinase. Thus, CD19 serves as a surrogate kinase insert region for mIgM by providing the means for PI 3-kinase activation by nonreceptor PTKs.
Tuveson
D A
DA
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Carter
R H
RH
Soltoff
S P
SP
Fearon
D T
DT
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000378:metabolism*; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D001483:Base Sequence; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism*; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010716:Phosphatidylinositols / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
D015703:Antigens, CD; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte; D007075:Immunoglobulin M; D010716:Phosphatidylinositols; D014443:Tyrosine; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases