title: Nucleotide sequence and properties of the murine gamma 3 immunoglobulin heavy chain gene switch region: implications for successive C gamma gene switching.
abstract: During B lymphocyte differentiation, immunoglobulin heavy chain constant region (CH) genes undergo a unique series of DNA recombination events culminating in the CH class switch. CH switch (S) regions are located 2 kb 5' of each CH gene except delta (i.e. mu, gamma 3, gamma 1, gamma 2b, gamma 2a, epsilon and alpha). We describe the structural features of the gamma 3 switch region. Hybridization experiments show that S gamma 3 has remarkable homology to both S mu and other S gamma regions while S mu possesses limited homology to the other S gamma sequences. However, S mu possesses extensive sequence homology with S epsilon and S alpha. The nucleotide sequence of S gamma 3 reveals higher densities of S mu repetitive sequences (GAGCT and GGGGT) and another S region common sequence (YAGGTTG) than observed for S gamma 1, S gamma 2b or S gamma 2a. In addition, the conservation of S mu like repetitive sequences in S gamma regions is correlated with the 5' leads to 3' gamma gene order (i.e. S gamma 3 greater than S gamma 1 greater than S gamma 2b greater than S gamma 2a). A model is presented which suggests that the unique features of S gamma 3 may allow for successive switches from C mu to any C gamma gene.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant; D005796:Genes; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007142:Immunoglobulin gamma-Chains / Q000235:genetics*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009693:Nucleic Acid Hybridization; D013094:Spermatozoa
chemical_list: D004274:DNA, Recombinant; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007142:Immunoglobulin gamma-Chains; D004262:DNA Restriction Enzymes