Monomeric and Oligomeric Complexes of the B Cell Antigen Receptor

Immunity. 2000 Jul;13(1):5-14. doi: 10.1016/s1074-7613(00)00003-0.

Abstract

The current structural model of the B cell antigen receptor (BCR) describes it as a symmetric protein complex in which one membrane-bound immunoglobulin molecule (mIg) is noncovalently bound on each side by an Ig-alpha/Ig-beta heterodimer. Using peptide-tagged Ig-alpha proteins, blue native polyacrylamide gel electrophoresis (BN-PAGE), and biosynthetical labeling of B cells, we find that the mIg:Ig-alpha/Ig-beta complex has a stoichiometry of 1:1 and not 1:2. An anti-Flag stimulation of B cells coexpressing Flag-tagged and wild-type Ig-alpha proteins results in the phosphorylation of both Ig-alpha proteins, suggesting that on the surface of living B cells, several BCR monomers are in contact with each other. A BN-PAGE analysis after limited detergent lysis provides further evidence for an oligomeric BCR structure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / immunology*
  • CD79 Antigens
  • Cell Line
  • Digitonin
  • Electrophoresis, Polyacrylamide Gel / methods
  • Immunoglobulin D / immunology
  • Immunoglobulin M / immunology
  • Indicators and Reagents
  • Mice
  • Phosphorylation
  • Receptors, Antigen, B-Cell / genetics
  • Receptors, Antigen, B-Cell / immunology*
  • Solubility

Substances

  • Antigens, CD
  • CD79 Antigens
  • Cd79a protein, mouse
  • Cd79b protein, mouse
  • Immunoglobulin D
  • Immunoglobulin M
  • Indicators and Reagents
  • Receptors, Antigen, B-Cell
  • Digitonin