title: Surrogate light chain-dependent selection of Ig heavy chain V regions.
abstract: Bone marrow B cell precursors frequently rearrange the Ig heavy chain variable (VH) gene segment VH81X. It is puzzling, therefore, that mature B cells in adult mice rarely express mu-heavy chains bearing this VH gene segment. We show in this work in transformed pre-B cell lines that two VH81X/mu-chains that differ in their VH-D-JH joining sequences are not assembled covalently with the B cell precursor-specific surrogate light (SL) chain and are not expressed on the cell surface. From these findings, we propose that a B cell precursor clonally expands and proceeds to the next developmental stage only if it expresses a mu-chain with a VH domain that, together with the SL chain, directs the formation of a signal-transducing mu/SL chain membrane complex. Therefore, a checkpoint exists early in B cell development, at which SL chain not only screens B cell precursors for the presence of a full-length mu-chain, but also for a VH domain that promotes the assembly of a mu/SL chain complex.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics* / Q000276:immunology*; D002460:Cell Line; D005434:Flow Cytometry; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007147:Immunoglobulin Light Chains / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data
chemical_list: D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region