Abstract
Activation signals of lymphocytes are negatively regulated by the membrane molecules carrying the immunoreceptor tyrosine-based inhibition motif (ITIM). Upon tyrosine phosphorylation, ITIMs recruit SH2-containing phosphatases such as SHP-1, resulting in down-modulation of cell activation. We showed that the cytoplasmic domain of the CD72 molecule carries an ITIM and is associated in vitro with SHP-1 upon tyrosine phosphorylation. Moreover, cross-linking of B cell Ag receptor (BCR) enhances both tyrosine phosphorylation of CD72 and association of CD72 with SHP-1 in B cell line WEHI-231. These results indicate that CD72 recruits SHP-1 upon tyrosine phosphorylation induced by BCR signaling, suggesting that CD72 is a negative regulator of BCR signaling.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antigens, CD / physiology*
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Antigens, Differentiation, B-Lymphocyte / physiology*
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Intracellular Signaling Peptides and Proteins
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Mice
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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 / physiology*
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Receptors, Antigen, B-Cell / physiology
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Tumor Cells, Cultured
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Tyrosine / metabolism*
Substances
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Antigens, CD
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Antigens, Differentiation, B-Lymphocyte
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CD72 protein, human
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Intracellular Signaling Peptides and Proteins
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Receptors, Antigen, B-Cell
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Tyrosine
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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