Comparison of human B cell antigen receptor complexes: membrane-expressed forms of immunoglobulin (Ig)M, IgD, and IgG are associated with structurally related heterodimers

J Exp Med. 1992 Jun 1;175(6):1511-9. doi: 10.1084/jem.175.6.1511.

Abstract

We have recently reported that on human B lymphocytes, membrane IgM (mIgM) associates with a heterodimer of 47- and 37-kD polypeptides, the 47-kD subunit being encoded by the mb-1 gene. We show here that expression of mb-1, both at the mRNA and the protein level, is not restricted to IgM+ B cells but can also be found in IgM- pre-B cells and mIgM-IgG+ B cells. Membrane forms of IgD and IgG, isolated from freshly isolated human B cells and B cell lines, are expressed together with heterodimeric protein structures biochemically similar to the mIgM-associated polypeptides, and these were shown to comprise the products of the mb-1 and B29 genes, or homologous genes. Finally, all three classes of antigen receptors are linked to protein kinases, capable of phosphorylating the Ig-associated heterodimers. Our findings provide insight in the structural organization of the different antigen receptors on human B cells and have implications for their function.

Publication types

  • Comparative Study

MeSH terms

  • Antibodies, Monoclonal
  • B-Lymphocytes / immunology*
  • Blotting, Northern
  • Cell Line
  • Cell Membrane / immunology
  • Fluorescent Antibody Technique
  • Genes, Immunoglobulin*
  • Humans
  • Immunoglobulin D / analysis
  • Immunoglobulin D / genetics
  • Immunoglobulin D / metabolism*
  • Immunoglobulin G / analysis
  • Immunoglobulin G / genetics
  • Immunoglobulin G / metabolism*
  • Immunoglobulin M / analysis
  • Immunoglobulin M / genetics
  • Immunoglobulin M / metabolism*
  • Immunoglobulin lambda-Chains / analysis
  • Immunoglobulin mu-Chains / analysis
  • Macromolecular Substances
  • Molecular Weight
  • Palatine Tonsil / immunology
  • Phosphorylation
  • RNA / genetics
  • RNA / isolation & purification
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Antigen, B-Cell / analysis
  • Receptors, Antigen, B-Cell / metabolism*

Substances

  • Antibodies, Monoclonal
  • Immunoglobulin D
  • Immunoglobulin G
  • Immunoglobulin M
  • Immunoglobulin lambda-Chains
  • Immunoglobulin mu-Chains
  • Macromolecular Substances
  • RNA, Messenger
  • Receptors, Antigen, B-Cell
  • RNA