Structure of bovine immunoglobulin constant region heavy chain gamma 1 and gamma 2 genes.
Two bovine immunoglobulin constant region gamma heavy chain germline gene sequences are described. A gamma 1 gene was cloned from a lambda 2001 calf liver library screened with a human gamma 4 (pBRH4.1) probe and is contained in a 5.8 kb BamH1 hybridizing fragment. The gamma 2 gene was from an EMBL4 lambda library and is in a 6.6 kb BamH1 fragment. Each of these genes is arranged in four exons corresponding to the three CH domains and the hinge of gamma heavy chain genes; normal RNA splice and polyadenylation sites are present. The translated C-terminal peptide sequences of the genes match exactly the equivalent peptide sequences of bovine IgG1 and IgG2 heavy chains, identifying them as gamma 1 and gamma 2. The derived protein sequences reveal 96, 80 and 83% identity of amino acid residues between their CH1, CH2 and CH3 domains. Two adjacent cysteine residues encoded in the CH1 exons suggest that, as in rabbit gamma, an extra intra-chain disulphide bond occurs in the bovine gamma heavy chains. Significant DNA rearrangement in the hinge-CH2 region is evident in the bovine gamma 2 gene, with resultant deletion and substitution of amino acid residues in the lower hinge and N-terminal portion of the CH2 domain. The Fab-Fc interface of bovine IgG2 is predicted to be sterically blocked, relative to IgG1, which has implications for effector differences between the bovine gamma subclasses.
Symons
D B
DB
Agricultural and Food Research Council, Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K.
Clarkson
C A
CA
Beale
D
D
D000818:Animals; D001483:Base Sequence; D002417:Cattle / Q000276:immunology*; D004247:DNA / Q000032:analysis; D005091:Exons; D005803:Genes, Immunoglobulin; D052058:Hinge Exons; D007127:Immunoglobulin Constant Regions / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D012326:RNA Splicing
D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D004247:DNA