Abstract
CD22 is a membrane immunoglobulin (mIg)-associated protein of B cells. CD22 is tyrosine-phosphorylated when mIg is ligated. Tyrosine-phosphorylated CD22 binds and activates SHP, a protein tyrosine phosphatase known to negatively regulate signaling through mIg. Ligation of CD22 to prevent its coaggregation with mIg lowers the threshold at which mIg activates the B cell by a factor of 100. In secondary lymphoid organs, CD22 may be sequestered away from mIg through interactions with counterreceptors on T cells. Thus, CD22 is a molecular switch for SHP that may bias mIg signaling to anatomic sites rich in T cells.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Antigens, CD / immunology*
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Antigens, CD / metabolism
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Antigens, Differentiation, B-Lymphocyte / immunology*
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Antigens, Differentiation, B-Lymphocyte / metabolism
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B-Lymphocytes / immunology*
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Cell Adhesion Molecules*
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Cells, Cultured
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Humans
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Immunoglobulin M / immunology
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Intracellular Signaling Peptides and Proteins
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Lectins*
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Lymphocyte Activation*
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Mice
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Molecular Sequence Data
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Phosphorylation
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Protein Tyrosine Phosphatase, Non-Receptor Type 11
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Protein Tyrosine Phosphatase, Non-Receptor Type 6
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Protein Tyrosine Phosphatases / metabolism*
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Recombinant Proteins / metabolism
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Sialic Acid Binding Ig-like Lectin 2
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Signal Transduction
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Tumor Cells, Cultured
Substances
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Antigens, CD
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Antigens, Differentiation, B-Lymphocyte
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CD22 protein, human
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Cd22 protein, mouse
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Cell Adhesion Molecules
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Immunoglobulin M
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Intracellular Signaling Peptides and Proteins
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Lectins
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Recombinant Proteins
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Sialic Acid Binding Ig-like Lectin 2
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PTPN11 protein, human
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PTPN6 protein, human
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Protein Tyrosine Phosphatase, Non-Receptor Type 11
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Protein Tyrosine Phosphatase, Non-Receptor Type 6
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Protein Tyrosine Phosphatases
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Ptpn11 protein, mouse
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Ptpn6 protein, mouse