Abstract
The B cell antigen receptor (BCR) consists of the membrane-bound immunoglobulin (Ig) molecule as antigen-binding subunit and the Ig-alpha/Ig-beta heterodimer as signaling subunit. BCR signal transduction involves activation of protein tyrosine kinases (PTKs) and phosphorylation of several proteins, only some of which have been identified. The phosphorylation of these proteins can be induced by exposure of B cells either to antigen or to the tyrosine phosphatase inhibitor pervanadate/H2O2. One of the earliest substrates in B cells is a 65-kD protein, which we identify here as a B cell adaptor protein. This protein, named SLP-65, is part of a signaling complex involving Grb-2 and Vav and shows homology to SLP-76, a signaling element of the T cell receptor. In pervanadate/H2O2-stimulated cells, SLP-65 becomes phosphorylated only upon expression of the BCR. These data suggest that SLP-65 is part of a BCR transducer complex.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing*
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Amino Acid Sequence
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Animals
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B-Lymphocytes / drug effects
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B-Lymphocytes / metabolism*
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Base Sequence
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Carrier Proteins*
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Cell Cycle Proteins*
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DNA, Complementary
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Enzyme Inhibitors / pharmacology
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GRB2 Adaptor Protein
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Humans
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Hydrogen Peroxide / pharmacology
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Immunoglobulin delta-Chains / metabolism
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Immunoglobulin mu-Chains / metabolism
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Molecular Sequence Data
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Phosphoproteins / genetics
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Phosphoproteins / metabolism*
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Protein-Tyrosine Kinases / metabolism
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Proteins / metabolism
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-vav
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Rabbits
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Receptors, Antigen, B-Cell / metabolism*
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Signal Transduction*
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Tumor Cells, Cultured
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Vanadates / pharmacology
Substances
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Adaptor Proteins, Signal Transducing
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B cell linker protein
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Carrier Proteins
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Cell Cycle Proteins
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DNA, Complementary
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Enzyme Inhibitors
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GRB2 Adaptor Protein
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GRB2 protein, human
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Immunoglobulin delta-Chains
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Immunoglobulin mu-Chains
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Phosphoproteins
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Proteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-vav
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Receptors, Antigen, B-Cell
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VAV1 protein, human
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pervanadate
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Vanadates
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Hydrogen Peroxide
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Protein-Tyrosine Kinases