In: The EMBO Journal, 6 (1987), Nr. 6. pp. 1677-1683

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Abstract

The gene for murine Ia-associated invariant (1i) chains (1131 and 1i41) was characterized by sequence analysis. The gene extends over - 9 kb and is organized in nine exons. Exon 1 encodes the 5' untranslated region and the cytoplasmic segment, exon 2 the membrane spaniing segment and adjacent amino acids and exons 3- 8 the extracytoplasmic portion of 1131. 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 li-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 1141 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.