Related Experiment Video
Updated: Aug 14, 2026
Induction and Assessment of Class Switch Recombination in Purified Murine B Cells
Published on: August 14, 2010
Characterization of components of the murine B cell receptor complex and their role in anti-Ig stimulation
1Paul-Ehrlich-Institut, Langen, Germany.
Signal transduction in B cells is mediated by B cell receptor (BCR) complexes that are composed of membrane immunoglobulins (mIg) and additional proteins (e.g. Ig-alpha and Ig-beta) that have been implicated with several aspects of B cell activation. In this paper, experiments are described that have been designed to characterize new components of the BCR and to elucidate their involvement in B cell activation directly after the binding of anti-Ig. The data obtained prove the assumption that IgM is degraded after internalization. Neither immunoglobulin nor the Ig-alpha/beta heterodimer are re-expressed after they have disappeared from the cell surface. The newly detected Ig-alpha associated proteins are neither degradation products of immunoglobulins nor different forms of Ig-alpha or Ig-beta. In addition, they are not recognized by antibodies against any of the kinases known to date. The mIg molecules are linked to the cytoskeleton and internalized. On the other hand, the additional Ig-alpha associated proteins as well as the Ig-alpha/beta heterodimer could not be detected in the detergent-insoluble fraction. The former molecules remain on the B cell surface where they are attached to the unaffected isotype and might interact with downstream members of the signalling cascade. In addition, evidence is presented that the internalization of the receptor complex is not necessary for signal transduction and B cell activation. From these results the authors conclude that the BCR complexes are removed from the cell surface after binding of ligands, probably to prevent further activation of this cell, while the Ig-alpha associated proteins interact with the intracellular components of the signal transduction pathway to promote the further activation of the B cells.
Signal transduction in B cells is mediated by B cell receptor (BCR) complexes that are composed of membrane immunoglobulins (mIg) and additional proteins (e.g. Ig-alpha and Ig-beta) that have been implicated with several aspects of B cell activation. In this paper, experiments are described that have been designed to characterize new components of the BCR and to elucidate their involvement in B cell activation directly after the binding of anti-Ig. The data obtained prove the assumption that IgM is degraded after internalization. Neither immunoglobulin nor the Ig-alpha/beta heterodimer are re-expressed after they have disappeared from the cell surface. The newly detected Ig-alpha associated proteins are neither degradation products of immunoglobulins nor different forms of Ig-alpha or Ig-beta. In addition, they are not recognized by antibodies against any of the kinases known to date. The mIg molecules are linked to the cytoskeleton and internalized. On the other hand, the additional Ig-alpha associated proteins as well as the Ig-alpha/beta heterodimer could not be detected in the detergent-insoluble fraction. The former molecules remain on the B cell surface where they are attached to the unaffected isotype and might interact with downstream members of the signalling cascade. In addition, evidence is presented that the internalization of the receptor complex is not necessary for signal transduction and B cell activation. From these results the authors conclude that the BCR complexes are removed from the cell surface after binding of ligands, probably to prevent further activation of this cell, while the Ig-alpha associated proteins interact with the intracellular components of the signal transduction pathway to promote the further activation of the B cells.
Related Concept Videos
01:10Antibody Structure
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
01:10Antibody Structure
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
01:28Diversity of Antigen Receptors
Before encountering any antigen, lymphocytes express these receptors. On B cells, the antigen receptor is a membrane-bound antibody molecule called BCR; on T cells, it is a T cell receptor or TCR. B and T cell receptors are composed of two...
01:22T Cell Activation and Clonal Selection
Naive T cells that have not yet encountered an antigen express two primary CD...
01:24B Cell Activation and Differentiation
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...
01:25Antibody Structure and Classes
The basic structure of an antibody consists of four protein chains: two identical heavy chains and two identical light chains. These chains are held together by disulfide bonds and other non-covalent interactions, forming a Y-shaped structure.