title: Molecular diversity of the human T-gamma constant region genes.
abstract: The human T cell antigen-receptor gamma chain, which is expressed on the surface of a subpopulation of CD3+ T lymphocytes, exhibits size polymorphism and varies in its ability to form disulfide bonds with a second polypeptide. Analysis of both genomic and complementary DNA clones encoding the human gamma polypeptide shows differences in lengths of the coding portions of the two constant region genes, C gamma 1 and C gamma 2. A single second-exon segment is always present in the C gamma 1 gene. C gamma 2 alleles containing either duplicated or triplicated second-exon segments are present in the normal human population and are expressed as messenger RNAs. Furthermore, a cysteine residue, encoded by the second exon of C gamma 1 and probably involved in interchain disulfide bridging, is absent in all C gamma 2 second-exon segments. These differences between C gamma 1 and the two alleles of C gamma 2 may explain the variability in molecular weight and disulfide bonding of gamma molecules expressed in different cells.
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000235:genetics; D005802:Genes, MHC Class II; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007142:Immunoglobulin gamma-Chains / Q000235:genetics*; D007136:Immunoglobulins / Q000235:genetics*; D011110:Polymorphism, Genetic; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*
chemical_list: D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007142:Immunoglobulin gamma-Chains; D007136:Immunoglobulins; D011948:Receptors, Antigen, T-Cell; D004247:DNA