Abstract
Crosslinking of membrane-bound immunoglobulins, which are B-cell antigen receptors, causes proliferation and differentiation of B cells or inhibition of their growth. The receptor-mediated signaling involves tyrosine phosphorylation of cellular proteins and rapid activation of Src-like kinases. The amino acid sequences of five proteolytic peptides of p75, a major substrate of protein-tyrosine(s) in the signaling, showed that p75 is the human HS1 gene product. The HS1 gene is expressed specifically in hematopoietic cells and encodes p75HS1, which carries both helix-turn-helix and Src homology 3 motifs. p75HS1 showed rapid tyrosine phosphorylation and association with a Src-like kinase, Lyn, after crosslinking of membrane-bound IgM. Thus, p75HS1 may be an important substrate of Lyn and possibly other protein-tyrosine kinases upon B-cell antigen receptor-mediated signaling.
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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Antibodies
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Antibodies, Monoclonal
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B-Lymphocytes / immunology*
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B-Lymphocytes / physiology
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Blood Proteins / isolation & purification
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Blood Proteins / metabolism*
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Electrophoresis, Polyacrylamide Gel
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Humans
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Immunoblotting
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Leukocyte Common Antigens / isolation & purification
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Molecular Sequence Data
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Molecular Weight
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Peptide Fragments / isolation & purification
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Phosphoproteins / isolation & purification
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Phosphoproteins / metabolism
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Phosphotyrosine
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Protein-Tyrosine Kinases / metabolism*
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Receptors, Antigen, T-Cell / physiology*
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Signal Transduction*
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Tumor Cells, Cultured
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Tyrosine / analogs & derivatives
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Tyrosine / analysis
Substances
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Adaptor Proteins, Signal Transducing
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Antibodies
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Antibodies, Monoclonal
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Blood Proteins
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HCLS1 protein, human
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Peptide Fragments
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Phosphoproteins
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Receptors, Antigen, T-Cell
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Phosphotyrosine
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Tyrosine
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Protein-Tyrosine Kinases
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Leukocyte Common Antigens