Galectin‐related protein is a kind of lectin without canonical activity that regulates cell adhesion and cell growth. In this study, a novel galectin‐related protein B (OnGRPB) was identified from Nile tilapia (Oreochromis niloticus). The open reading frame of OnGRPB was 438 bp and encoded a peptide of 145 amino acids. The deduced protein sequence of OnGRPB possessed a conserved carbohydrate recognition domain (CRD) with partial sugar binding sites (N‐R, V‐N and W‐E) and shared high identities with other fish GRPB proteins. The qRT‐PCR analysis found that OnGRPB was widely distributed in various tissues and monocyte/macrophages (Mo/MΦ) of healthy tilapia. After Streptococcus agalactiae infection, OnGRPB transcripts were significantly up‐regulated in liver, spleen, head kidney and Mo/MΦ. The recombinant OnGRPB protein (rOnGRPB) had the binding activity and agglutination ability to bacteria. Also, rOnGRPB could modulate antibacterial activity and inflammatory factor expression of Mo/MΦ. These data collectively indicate that OnGRPB plays roles in the immune response of Nile tilapia against bacterial infection.

中文翻译：

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尼罗罗非鱼半乳糖凝集素相关蛋白B的特征和功能分析，涉及细菌感染的免疫反应

半乳凝素相关蛋白是一种不具有规范活性的凝集素，可调节细胞黏附和细胞生长。在这项研究中，从尼罗罗非鱼（Oreochromis niloticus）中鉴定了一种新型的半乳糖凝集素相关蛋白B（OnGRPB）。OnGRPB的开放阅读框为438bp，并编码145个氨基酸的肽。推导的OnGRPB蛋白质序列具有保守的碳水化合物识别结构域（CRD），具有部分糖结合位点（N-R，V-N和W-E），并且与其他鱼类GRPB蛋白质具有高度同一性。qRT-PCR分析发现OnGRPB广泛分布在健康罗非鱼的各种组织和单核细胞/巨噬细胞（Mo /MΦ）中。后无乳链球菌感染，肝，脾，头肾和Mo /MΦ中OnGRPB转录本显着上调。重组OnGRPB蛋白（rOnGRPB）具有与细菌的结合活性和凝集能力。此外，rOnGRPB可以调节Mo /MΦ的抗菌活性和炎症因子表达。这些数据共同表明OnGRPB在尼罗罗非鱼针对细菌感染的免疫反应中发挥作用。