Abstract
BIT (a brain immunoglobulin-like molecule with tyrosine-based activation motifs) is a brain-specific membrane protein which has two cytoplasmic TAMs (tyrosine-based activation motifs). Using the Far Western blotting technique, we detected association of a 70-kDa protein with the tyrosine-phosphorylated TAMs of BIT. A mouse brain cDNA library in lambdagt11 was screened for this association, and two positive clones encoding tyrosine phosphatase SH-PTP2 were isolated. SH-PTP2 has two SH2 domains and is believed to function as a positive mediator in receptor tyrosine kinase signaling. SH-PTP2 and BIT were coimmunoprecipitated from phosphorylated rat brain lysate, and BIT was a major tyrosine-phosphorylated protein associated with SH-PTP2 in this lysate. This interaction was also observed in Jurkat T cells transfected with BIT cDNA depending on tyrosine phosphorylation of BIT. Bisphosphotyrosyl peptides corresponding to BIT-TAMs stimulated SH-PTP2 activity 33-35-fold in vitro, indicating that two SH2 domains of SH-PTP2 simultaneously interact with two phosphotyrosines of BIT-TAM. Our findings suggest that the tyrosine phosphorylation of BIT results in stimulation of the signal transduction pathway promoted by SH-PTP2 and that BIT is probably a major receptor molecule in the brain located just upstream of SH-PTP2.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Blotting, Western
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Brain / metabolism*
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Cell Line
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DNA Primers
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Enzyme Activation
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Humans
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Intracellular Signaling Peptides and Proteins
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Mice
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Models, Structural
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / isolation & purification
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Nerve Tissue Proteins / metabolism*
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Peptide Fragments / chemistry
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Phosphopeptides / chemical synthesis
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Phosphopeptides / chemistry
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Phosphorylation
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Polymerase Chain Reaction
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Protein Conformation
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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 / chemistry
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Protein Tyrosine Phosphatases / metabolism*
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Rats
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Receptors, Antigen / chemistry
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Receptors, Antigen / isolation & purification
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Receptors, Antigen / metabolism*
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / isolation & purification
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Recombinant Fusion Proteins / metabolism
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Signal Transduction
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Transfection
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Tyrosine*
Substances
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DNA Primers
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Intracellular Signaling Peptides and Proteins
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Nerve Tissue Proteins
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Peptide Fragments
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Phosphopeptides
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Receptors, Antigen
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Recombinant Fusion Proteins
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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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Ptpn11 protein, rat
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Ptpn6 protein, mouse
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Ptpn6 protein, rat
Associated data
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GENBANK/D38468
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GENBANK/D84372