title: Molecular genetics of immunoglobulins.
abstract: At the protein level, antibodies show several types of variability. One is the diversity of the variable (V) regions of heavy (H) and light (L) chains, leading to antibody-combining site specificity; another is the existence of two types of light chain (kappa and lambda); a third is the diversity of heavy chain-constant (CH) regions associated with different effector functions. At the DNA level, V-region variability is coded partly through the large number of VL- and VH-region genes and partly generated by integrating complete V genes from combinations of shorter segments (VL-JL for the light chain, VH-D-JH for the heavy chains), together with somatic mutational events (Tonegawa, 1983). kappa, lambda and H chains are coded independently on different chromosomes and have their own V- and C-region genes (Honjo, 1983). CH-region diversity results from a set of CH genes corresponding to the different Ig subclasses. During B-cell development, rearrangement of DNA occurs both in the VL/VH- and CH-region genes. V-region rearrangements take place at the pre-B-cell stage and produce the complete V-region genes for the heavy and light chains which will permanently characterize an individual clone; CH-region rearrangements enable mature B cells to secrete their V regions on different Ig classes (class switching). This article will review the structure and organization of V and C genes and the control of their expression.
mesh_terms: D000818:Animals; D000916:Antibody Diversity; D001402:B-Lymphocytes / Q000276:immunology; D005786:Gene Expression Regulation; D005803:Genes, Immunoglobulin; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007136:Immunoglobulins / Q000235:genetics*; D051379:Mice; D011995:Recombination, Genetic
chemical_list: D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D007136:Immunoglobulins