CD209（也称为DC-SIGN，全称Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin）是一种主要表达于树突状细胞（Dendritic Cells, DCs）和巨噬细胞表面的C型凝集素受体（C-type lectin receptor），属于CLEC4（C-type lectin domain family 4）基因家族。该家族成员通常含有碳水化合物识别结构域（CRD），能够识别病原体表面的糖基化模式（如病毒、细菌或真菌的糖蛋白），参与先天免疫应答。CD209的生物学功能包括介导病原体识别（如HIV、埃博拉病毒、结核分枝杆菌等）、促进免疫细胞间黏附（如与T细胞表面的ICAM-3结合）以及调节炎症反应。其作用位点主要在细胞膜表面，通过内化病原体或传递信号激活下游免疫通路。突变可能导致CD209功能异常，例如某些单核苷酸多态性（SNPs）与HIV感染易感性或结核病风险相关。若CD209过表达，可能增强病原体捕获能力但同时也可能被某些病毒（如HIV）劫持以促进感染；而低表达则可能削弱免疫监视功能。该基因与传染病（如艾滋病、结核）、自身免疫病（如类风湿关节炎）和癌症（如肿瘤免疫逃逸）有关联。CLEC4家族共性为通过糖识别参与免疫防御，部分成员还具有抗原提呈或细胞迁移调控功能。专业术语解释：树突状细胞是专职抗原提呈细胞，负责启动适应性免疫；C型凝集素是一类依赖钙离子的糖结合蛋白；单核苷酸多态性指DNA序列中单个碱基的变异。

This gene encodes a transmembrane receptor and is often referred to as DC-SIGN because of its expression on the surface of dendritic cells and macrophages. The encoded protein is involved in the innate immune system and recognizes numerous evolutionarily divergent pathogens ranging from parasites to viruses with a large impact on public health. The protein is organized into three distinct domains: an N-terminal transmembrane domain, a tandem-repeat neck domain and C-type lectin carbohydrate recognition domain. The extracellular region consisting of the C-type lectin and neck domains has a dual function as a pathogen recognition receptor and a cell adhesion receptor by binding carbohydrate ligands on the surface of microbes and endogenous cells. The neck region is important for homo-oligomerization which allows the receptor to bind multivalent ligands with high avidity. Variations in the number of 23 amino acid repeats in the neck domain of this protein are rare but have a significant impact on ligand binding ability. This gene is closely related in terms of both sequence and function to a neighboring gene (GeneID 10332; often referred to as L-SIGN). DC-SIGN and L-SIGN differ in their ligand-binding properties and distribution. Alternative splicing results in multiple variants.[provided by RefSeq, Feb 2009]

这个基因编码的跨膜受体，并且通常被称为DC-SIGN，因为它的树突状细胞和巨噬细胞的表面上表达的。所编码的蛋白质是参与先天免疫系统，并认识许多进化分歧病原体从寄生虫对公众健康有很大的影响的病毒。该蛋白质被分为三个不同的结构域：N-末端跨膜结构域，串联重复颈域和C型凝集素的碳水化合物识别结构域。由C型凝集素和颈结构域的胞外区具有双重功能作为病原体识别受体和由微生物和内源性细胞的表面上的结合糖的配体的细胞粘附受体。颈部区域为同型寡聚允许受体结合的多价配体以高亲合力重要。在此蛋白质的颈部域23氨基酸重复数变化是罕见的，但对配体结合的能力的显著影响。该基因是在这两个序列和功能到相邻基因的术语（;通常被称为L-SIGN GeneID 10332）密切相关的。 DC-SIGN和L-SIGN在其配体结合特性和分布不同。选择性剪接产生多个变种。[由RefSeq的，2009年2月提供]

CD209基因在不同组织中的表达：    [UniProt]

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