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CD22 associates with the human surface IgM-B-cell antigen receptor complex

C Leprince1, K E Draves, R L Geahlen

  • 1Department of Microbiology, University of Washington, Seattle 98195.

Proceedings of the National Academy of Sciences of the United States of America
|April 15, 1993
PubMed

Insights

The B-cell molecule CD22 modulates B-cell receptor (BCR) signaling. CD22 is rapidly phosphorylated and associates with the sIgM-BCR complex, indicating its role as a signaling partner.

Area of Science:

  • Immunology
  • Cell Signaling
  • Molecular Biology

Background:

  • The B-cell surface molecule CD22 regulates signaling pathways initiated by the B-cell receptor (BCR).
  • Understanding the molecular basis of CD22 interaction with the BCR complex is crucial for deciphering B-cell activation and function.

Purpose of the Study:

  • To investigate the interaction between CD22 and the human surface IgM (sIgM)-BCR complex.
  • To identify the molecular components and signaling events involved in CD22-mediated modulation of BCR signaling.

Main Methods:

  • B-cell lysis in digitonin followed by coimmunoprecipitation.
  • In vitro kinase assays to detect phosphorylation of CD22.
  • Immunoblot analysis using specific antibodies to identify protein components.

Main Results:

  • CD22 coimmunoprecipitated a kinase activity that phosphorylated CD22 on tyrosine residues.
  • Phosphorylated CD22 was found within the sIgM-BCR complex, alongside Ig alpha/mb-1, Ig beta/B29, and PTK72.
  • Rapid and significant phosphorylation of CD22 upon sIgM cross-linking was observed.

Conclusions:

  • CD22 is a key signaling partner within the sIgM-BCR complex.
  • The phosphorylation of CD22 is a critical event in its modulation of BCR signaling.
  • CD22's ARHI motif suggests a role in antigen recognition pathways.

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