Niimi M, Nakai Y, Aida Y
Laboratory of Gene Technology and Safety, Tsukuba Life Science Center, Institute of Physical and Chemical Research (RIKEN), Ibaraki, Japan.
Biochem Biophys Res Commun. 1996 May 6;222(1):7-12. doi: 10.1006/bbrc.1996.0689.
Four overlapping cDNA clones encoding the bovine invariant chain (Ii) were isolated and characterized. The bovine Ii cDNA clone, NI3 with a 1,381-bp insert, encoded a translated product of 204 amino acids. The amino acid sequences deduced from this clone revealed that the bovine Ii gene is more closely related to human Ii gene than to genes for rodents, such as mouse and rat, but lacked 10 amino acids of the 3' end of the extracellular domain comparable to those in proteins from other species. Of interest is that the class-II-associated invariant chain peptide (CLIP) segment is present in the protein encoded by NI3, and this region exhibits a high degree of overall similarity to sequences encoded by human, mouse and rat, suggesting that bovine CLIP may have the biological function of CLIP binding to MHC class II molecules. Thus, it seems likely that this cDNA clone encodes a functional product which might perform an important function in MHC class II antigen presentation, as previously established in studies in mouse and man.
分离并鉴定了四个编码牛恒定链（Ii）的重叠cDNA克隆。牛Ii cDNA克隆NI3插入片段为1381bp，编码一个由204个氨基酸组成的翻译产物。从该克隆推导的氨基酸序列表明，牛Ii基因与人Ii基因的关系比与啮齿动物（如小鼠和大鼠）的基因更为密切，但在细胞外结构域3'端缺少10个氨基酸，这与其他物种蛋白质中的相应氨基酸不同。有趣的是，II类相关恒定链肽（CLIP）片段存在于NI3编码的蛋白质中，并且该区域与人类、小鼠和大鼠编码的序列具有高度的整体相似性，这表明牛CLIP可能具有CLIP与MHC II类分子结合的生物学功能。因此，这个cDNA克隆似乎编码一种功能性产物，它可能在MHC II类抗原呈递中发挥重要作用，正如先前在小鼠和人类研究中所证实的那样。
