Berg S F, Dissen E, Westgaard I H, Fossum S
Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Norway.
Eur J Immunol. 1998 Feb;28(2):444-50. doi: 10.1002/(SICI)1521-4141(199802)28:02<444::AID-IMMU444>3.0.CO;2-M.
Two different lectin-like receptors for MHC class I molecules have so far been identified on natural killer (NK) cells, the Ly-49 homodimeric receptors in mice and the NKG2/CD94 heterodimeric receptors in humans. The recent identification of a rat CD94 orthologue implied that NK cell receptors equivalent to NKG2/CD94 also exist in rodents. Here we describe the cDNA cloning of two rat genes homologous to members of the human NKG2 multigene family. The deduced rat NKG2A protein contains a cytoplasmic immunoreceptor tyrosine-based inhibition motif (ITIM), whereas the cytoplasmic tail of rat NKG2C lacks ITIM. The genes map to the rat NK gene complex and are selectively expressed by NK cells. The expression is strain dependent, with high expression in DA and low in PVG NK cells, correlating with the expression of rat CD94. Ly-49 genes have previously been identified in the rat, and the existence of rat NKG2 genes in addition to a CD94 orthologue suggests that NK cell populations utilize different C-type lectin receptors for MHC class I molecules in parallel.
到目前为止，在自然杀伤（NK）细胞上已鉴定出两种不同的MHC I类分子凝集素样受体，即小鼠中的Ly-49同型二聚体受体和人类中的NKG2/CD94异源二聚体受体。最近对大鼠CD94同源物的鉴定表明，啮齿动物中也存在与NKG2/CD94等效的NK细胞受体。在此，我们描述了与人类NKG2多基因家族成员同源的两个大鼠基因的cDNA克隆。推导的大鼠NKG2A蛋白含有基于免疫受体酪氨酸的抑制基序（ITIM），而大鼠NKG2C的胞质尾缺乏ITIM。这些基因定位于大鼠NK基因复合体，并由NK细胞选择性表达。其表达具有品系依赖性，在DA中高表达，在PVG NK细胞中低表达，这与大鼠CD94的表达相关。此前已在大鼠中鉴定出Ly-49基因，除了CD94同源物外，大鼠NKG2基因的存在表明NK细胞群体同时利用不同的C型凝集素受体来识别MHC I类分子。
