Association of B Cell Antigen Receptor with Protein Tyrosine Kinase Lyn

Abstract

Antigen is thought to cross-link membrane-bound immunoglobulins (Igs) of B cells, causing proliferation and differentiation or the inhibition of growth. Protein tyrosine kinases are probably involved in signal transduction for cell proliferation and differentiation. The Src-like protein tyrosine kinase Lyn is expressed preferentially in B cells. The Lyn protein and its kinase activity could be coimmunoprecipitated with IgM from detergent lysates. Cross-linking of membrane-bound IgM induced a rapid increase in tyrosine phosphorylation of at least ten distinct proteins of B cells. Thus, Lyn is physically associated with membrane-bound IgM, and is suggested to participate in antigen-mediated signal transduction.

Involvement of p130Cas and p105HEF1, a Novel Cas-like Docking Protein, in a Cytoskeleton-dependent Signaling Pathway Initiated by Ligation of Integrin or Antigen Receptor on Human B Cells

“…Alternatively, the C-terminal region of Cas may be capable of mediating heterodimerization with HEF1 (24), and therefore, the Lyn immunoprecipitation may involve a ternary Lyn⅐Cas⅐HEF1 complex. Lyn kinase activity is stimulated following both BCR ligation (30) and as shown here following ␤1 integrin ligation, suggesting that Lyn may be a kinase for Cas/HEF1. In support of this is that Lyn kinase could phosphorylate Cas/HEF1 in vitro when mixed prior to the kinase assay.…”

“…Activation of p53/56 Lyn following ␤1 Integrin Cross-linking on Human Tonsillar B Cells-In addition to BCR ligation, a recent report has shown that Lyn kinase tyrosine phosphorylation is increased following integrin ligation in human B cell lines (30). Therefore, we investigated whether Lyn activation was also increased following ␤1 integrin ligation in normal FIG.…”

IL‐2‐induced gene expression of protein‐tyrosine phosphatase LC‐PTP requires acidic and serine‐rich regions within IL‐2 receptor β chain

“…For example, p56~Ckassociates with CD4/CD8 in T-cells, p59 fy" with the T-cell receptor complex, and p56 lyn with the B-cell antigen receptor [2][3][4]. Proliferation of T-cells is triggered by the interaction of IL-2 with IL-2 receptor (IL-2R) which consists of three distinct subunits, IL-2R~, IL-2Rfl, and IL-2Rz [5].…”

The major form of protein tyrosine kinase in the dog prostate is expressed by a 50 kDa polypeptide

“…More recently, the association of low-M~ PTKs with specific cell surface proteins (e.g. Ick-CD4/CDS; lck-in:erleukin-2 receptor; fyn-T cell antigen receptor; lyn-B cell antigen receptor) was demonstrated to play an important role in the activation of the immunologic response of lymphocytes [5][6][7][8]. ~umerous PTKs with unknown functions are also distributed elsewhere than in membranes [9][10][11]; this is the case of human and dog prostates whose PTK activity, mainly distributed in cytosolic fractions, migrates upon gel filtration as entities of 44-50 kDa Abbreviations: PTK, protein tyrosine kinas¢; SDS, sodium dodecyl sulfate; PAGE, polyacryiamide gel electrophoresis; polyGT, polymer of sodium glutamate and tyrosine; pY, phosphotyrosine; pS, phosphoserine; pT, phosphothreonine; QMA, quaternary methyl amine; Cts° octadodeeyl; 2D, two-dlmenslonal.…”