title: Primary structure of the gene for the murine Ia antigen-associated invariant chains (Ii). An alternatively spliced exon encodes a cysteine-rich domain highly homologous to a repetitive sequence of thyroglobulin.
abstract: The gene for murine Ia-associated invariant (Ii) chains (Ii31 and Ii41) was characterized by sequence analysis. The gene extends over approximately 9 kb and is organized in nine exons. Exon 1 encodes the 5' untranslated region and the cytoplasmic segment, exon 2 the membrane spanning segment and adjacent amino acids and exons 3-8 the extracytoplasmic portion of Ii31. Putative promoter sequences were found upstream of the start of the coding sequence. Between exons 6 and 7 an additional, alternatively spliced exon 6b has been identified. This exon is spliced into the mRNA coding for the Ii-related Ii41 protein. Exon 6b encodes a cysteine-rich domain of 64 amino acids. It shows a remarkably high homology to the repetitive elements in thyroglobulin, a precursor for thyroid hormone. Based on this homology, it is suggested that this domain (TgR) in Tg and in Ii41 may play a role either in hormone formation or as a carrier in the transport of molecules (thyroid hormone or processed antigen respectively) between intracellular compartments.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003545:Cysteine; D004262:DNA Restriction Enzymes; D005091:Exons; D005796:Genes; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D051379:Mice; D012326:RNA Splicing; D012689:Sequence Homology, Nucleic Acid; D013954:Thyroglobulin / Q000235:genetics*
chemical_list: D000949:Histocompatibility Antigens Class II; D013954:Thyroglobulin; D004262:DNA Restriction Enzymes; D003545:Cysteine