Tyrosine phosphorylation of CD22 during B cell activation

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Science  06 Nov 1992:
Vol. 258, Issue 5084, pp. 1001-1004
DOI: 10.1126/science.1279802


Ligation of the antigen receptor on B cells induces the rapid phosphorylation of tyrosine on a number of cellular proteins. A monoclonal antibody that recognized a tyrosine-phosphorylated cell surface protein that was present in activated B cells was generated. Amino acid sequence analysis showed that this 140-kilodalton protein was CD22, a B cell-specific cell surface glycoprotein and putative extracellular ligand of the protein tyrosine phosphatase CD45. Tyrosine phosphorylation of CD22 may be important in B cell signal transduction, possibly through regulation of the adhesiveness of activated B cells.