Sato Akie, Mayer Werner E, Overath Peter, Klein Jan
Max-Planck-Institut für Biologie, Abteilung Immungenetik and Abteilung Membranbiochemie, Corrensstrasse 42, D-72076 Tübingen, Germany.
Proc Natl Acad Sci U S A. 2003 Jun 24;100(13):7779-84. doi: 10.1073/pnas.1235938100. Epub 2003 Jun 11.
Mammalian natural killer (NK) cells are cytotoxic lymphocytes that express receptors specific for MHC class I molecules. The NK cell receptors belong to two structurally unrelated families, the killer cell Ig-like receptors and the killer cell C-type lectin receptors. We describe a cDNA clone derived from the bony (cichlid) fish Paralabidochromis chilotes and show that it encodes a protein related to the CD94/NK cell group 2 (NKG2) subfamily of the killer cell C-type lectin receptors. The gene encoding this receptor in a related species, Oreochromis niloticus, has a similar structure to the human CD94/NKG2 genes and is a member of a multigene cluster that resembles the mammalian NK cell gene complex. Thus, the CD94/NKG2 subfamily of NK cell receptors must have arisen before the divergence of fish and tetrapods and may have retained its function (possibly monitoring the expression of MHC class I molecules) for >400 million years.
哺乳动物的自然杀伤（NK）细胞是表达针对MHC I类分子特异性受体的细胞毒性淋巴细胞。NK细胞受体属于两个结构不相关的家族，即杀伤细胞免疫球蛋白样受体和杀伤细胞C型凝集素受体。我们描述了一个源自硬骨（丽鱼科）鱼类马拉维口孵非鲫的cDNA克隆，并表明它编码一种与杀伤细胞C型凝集素受体的CD94/NK细胞组2（NKG2）亚家族相关的蛋白质。在相关物种尼罗罗非鱼中编码该受体的基因具有与人类CD94/NKG2基因相似的结构，并且是一个类似于哺乳动物NK细胞基因复合体的多基因簇的成员。因此，NK细胞受体的CD94/NKG2亚家族必定在鱼类和四足动物分化之前就已出现，并且可能在超过4亿年的时间里保留了其功能（可能是监测MHC I类分子的表达）。
