Combadiere C, Gao J, Tiffany H L, Murphy P M
Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Biochem Biophys Res Commun. 1998 Dec 30;253(3):728-32. doi: 10.1006/bbrc.1998.9849.
Human fractalkine and its apparent murine counterpart neurotactin are the only members identified so far of the CX3C subfamily of chemokines. Recently, a human fractalkine receptor was identified and named CX3CR1. Here we have identified a mouse counterpart of this receptor. The receptor was identified by analysis of a mouse genomic clone named PC2 isolated by homology hybridization using CX3CR1 as probe. Clone PC2 has a 354-codon open reading frame that has 83% amino acid identity to CX3CR1. PC2 RNA was abundant in brain and lung and comparatively less abundant in lung, liver, kidney, testis, and peripheral blood leukocytes, a pattern similar to that found for CX3CR1. The recombinant fractalkine, but no other chemokines tested, induced chemotaxis and transient increases in [Ca2+]i in HEK 293 cells transfected with PC2, whereas untransfected cells did not respond. Furthermore, fractalkine bound specifically to the transfected cells (Kd=4 nM). Thus, fractalkine is a functional ligand for this receptor and we propose to name it mCX3CR1 for murine CX3C chemokine receptor 1.
人类fractalkine及其明显的小鼠对应物神经趋化因子是迄今为止趋化因子CX3C亚家族中仅有的已鉴定成员。最近，一种人类fractalkine受体被鉴定出来并命名为CX3CR1。在此我们鉴定出了该受体的小鼠对应物。通过使用CX3CR1作为探针进行同源杂交分析从小鼠基因组中分离出的一个名为PC2的克隆来鉴定该受体。克隆PC2有一个354个密码子的开放阅读框，与CX3CR1有83%的氨基酸同一性。PC2 RNA在脑和肺中丰富，而在肺、肝、肾、睾丸和外周血白细胞中相对较少，这一模式与CX3CR1的情况相似。重组fractalkine，而非所测试的其他趋化因子，能诱导转染了PC2的HEK 293细胞发生趋化作用并使细胞内钙离子浓度([Ca2+]i)短暂升高，而未转染的细胞则无反应。此外，fractalkine能特异性结合转染细胞(Kd = 4 nM)。因此，fractalkine是该受体的功能性配体，我们建议将其命名为mCX3CR1，即小鼠CX3C趋化因子受体1。
