The pre-B-cell receptor

The pre-B-cell receptor (pre-BCR) is composed of two immunoglobulin μ heavy chains and two surrogate light chains, which associate with the signaling molecules Igα and Igβ (Igα/β). The production of a functional pre-BCR is the first checkpoint in the current model of B-cell development. The pre-BCR mediates signals resulting in heavy chain allelic exclusion, down-regulation of the recombination machinery, developmental progression, VH repertoire selection, proliferation and down-regulation of the surrogate light chain genes. Recent studies suggest that some of these processes could take place at an earlier stage in B-cell development than previously thought, and might not result from signals mediated by the pre-BCR.