title: Sigma region located between C mu and C delta genes of human immunoglobulin heavy chain: possible involvement of tRNA-like structure in RNA splicing.
abstract: Noncoding regions within the cluster of immunoglobulin heavy chain constant genes in the human genome contained a number of repeats. In the mu-delta intron, two repeating units were contained. One 442-base-long fragment located JH-mu intron (defined as "sigma mu(sigma mu)") occupied the position in the mu-delta intron. The other 1166-base-long fragment located somewhere in front of S (class switch) region of C gamma gene was also found in the mu-delta intron. We defined the repeats in the mu-delta intron as "SIGMA (sigma)". The polarities of the longer repeats in the genome were opposite between the mu-delta intron and the upstreams of C gamma genes. These inverted copies (defined as sigma gamma 3 and sigma gamma 4), located 6 kb upstream of their respective C gamma's, were apparently transcribed in vitro, via RNA polymerase III and transcripts should have contained tRNA-like structures. Small DNA fragments capable of encoding tRNA-like structures were also found in corresponding regions of mouse Ig C gamma cluster.
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D005803:Genes, Immunoglobulin; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D012320:RNA Polymerase III; D012326:RNA Splicing; D012343:RNA, Transfer / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D004247:DNA; D012343:RNA, Transfer; D012320:RNA Polymerase III