Abstract
We demonstrate that the CD19 receptor associates with the beta1 family integrin receptors on human B-cell precursors as well as mature B-lymphocytes, and engagement of the beta1 family integrin receptors with monoclonal antibody homoconjugates leads to rapid activation of the CD19-associated protein-tyrosine kinases (PTK) and results in hyperphosphorylation of CD19 on tyrosine residues. Our findings prompt the hypothesis that homoconjugate-induced integrin clustering may effect the approximation and, by intermolecular cross-phosphorylation, activation of the CD19-associated PTK and subsequent tyrosine phosphorylation of the CD19 receptor. The ability of the beta1 family integrin receptors to transmit a biochemical signal triggering the CD19-linked multifunctional PTK pathway provides a possible explanation for the pleiotropic biologic responses generated though adhesive VLA-4- and VLA-5-mediated contacts.
Highlights
Integrins are heterodimeric integral plasma membrane proteins that mediate cell-cell as well as cell-extracellular matrix adhesion [1,2,3,4]
We demonstrate that the CD19 receptor associates with the 1 family integrin receptors on human B-cell precursors as well as mature B-lymphocytes, and engagement of the 1 family integrin receptors with monoclonal antibody homoconjugates leads to rapid activation of the CD19-associated protein-tyrosine kinases (PTK) and results in hyperphosphorylation of CD19 on tyrosine residues
Cross-linking 1 Integrin Family Surface Adhesion Molecules VLA-4 and VLA-5 Induces Enhanced Tyrosine Phosphorylation of the CD19 Receptor—Recent studies demonstrated that signaling through these adhesion receptors leads to enhanced tyrosine phosphorylation of multiple protein substrates, suggesting the involvement of PTK in the generation of physiologically significant biochemical events after the ligation of the 1 family integrin receptors [4, 22,23,24,25,26,27,28]
Summary
Integrins are heterodimeric integral plasma membrane proteins that mediate cell-cell as well as cell-extracellular matrix adhesion [1,2,3,4]. We demonstrate that the CD19 receptor associates with the 1 family integrin receptors on human B-cell precursors as well as mature B-lymphocytes, and engagement of the 1 family integrin receptors with monoclonal antibody homoconjugates leads to rapid activation of the CD19-associated protein-tyrosine kinases (PTK) and results in hyperphosphorylation of CD19 on tyrosine residues.
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