title: Molecular basis of heavy-chain class switching and switch region deletion in an Abelson virus-transformed cell line.
abstract: We demonstrated that a subclone of an Abelson murine leukemia virus-transformed B-lymphoid cell line switched from mu to gamma 2b expression in vitro, by the classical recombination-deletion mechanism. In this line, the expressed VHDJH region and the C gamma 2b constant region gene were juxtaposed by a recombination event which linked the highly repetitive portions of the S mu and S gama 2b regions and resulted in the loss of the C mu gene from the intervening region. An additional recombination event in this subclone involved an internal deletion in the S mu region of the expressed (switched) allele. One end of this deletion occurred very close to the switch recombination point. Despite the recombination-deletion mechanism of switching, the gamma 2b-producing line retained two copies of the C mu gene and two copies of the sequence just 5' to the S gamma 2b recombination point. The possible significance of the retention of these sequences to the mechanism of class switching is discussed.
mesh_terms: D000011:Abelson murine leukemia virus; D000483:Alleles; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D002472:Cell Transformation, Viral; D002872:Chromosome Deletion; D004247:DNA / Q000032:analysis; D005786:Gene Expression Regulation; D007143:Immunoglobulin Heavy Chains / Q000032:analysis*; D007142:Immunoglobulin gamma-Chains / Q000032:analysis; D007148:Immunoglobulin mu-Chains / Q000032:analysis; D009052:Leukemia Virus, Murine; D051379:Mice; D011995:Recombination, Genetic
chemical_list: D007143:Immunoglobulin Heavy Chains; D007142:Immunoglobulin gamma-Chains; D007148:Immunoglobulin mu-Chains; D004247:DNA