C-type lectin (CTL) proteins contain special carbohydrate-recognition domains (CRDs) and play vital roles in activating the innate immune system. In this study, a CTL gene from freshwater yellow catfish (Pelteobagrus fulvidraco) was identified and named as PfCTL. Analysis revealed that the complete PfCTL cDNA was 718 bp in size, including a 42-bp 5′-untranslated region (UTR), 61-bp 3′-UTR, and 615-bp open reading frame (ORF) encoding a 204 amino acid polypeptide, which contained a signal peptide and CRD. The PfCTL protein contained two casein kinase II phosphorylation sites, four protein kinase C phosphorylation sites, and two N-myristoylation sites. The deduced PfCTL protein sequence has 37–83 % in comparison to CTL proteins from other fish. Further phylogenetic analysis revealed that PfCTL was closely related to the CTL of Ictalurus punctatus. Based on quantitative real-time polymerase chain reaction, the PfCTL gene was expressed in all tested tissues at different levels, with highest distribution in the spleen, followed by the head kidney, and lowest distribution in blood. After challenge with lipopolysaccharide and polyriboinosinic polyribocytidylic acid, the expression of PfCTL was up-regulated in the liver, spleen, head kidney, and blood at different time points. These results imply that this CTL gene may be an important pathogen pattern recognition molecule in the innate immune system of yellow catfish under pathogen stimulation.

C型凝集素（CTL）蛋白包含特殊的碳水化合物识别域（CRD），在激活先天免疫系统中起着至关重要的作用。在这项研究中，从淡水黄色cat鱼（Pelteobagrus fulvidraco）中鉴定出一个CTL基因，并将其命名为PfCTL。分析显示，完整的PfCTLcDNA大小为718 bp，包括一个42 bp的5'-非翻译区（UTR），61 bp的3'-UTR和615 bp的开放阅读框（ORF），它们编码一个204个氨基酸的多肽，其中包含一个信号肽和CRD。PfCTL蛋白包含两个酪蛋白激酶II磷酸化位点，四个蛋白激酶C磷酸化位点和两个N-肉豆蔻酰基化位点。与其他鱼类的CTL蛋白相比，推导的PfCTL蛋白序列具有37–83％。进一步的系统发育分析表明，pfctl的密切相关的CTL斑点叉尾鮰。基于定量实时聚合酶链反应，PfCTL该基因在所有测试组织中均以不同水平表达，在脾脏中分布最高，其次是头部肾脏，在血液中分布最低。在用脂多糖和聚核糖核酸聚核糖核酸攻击后，PfCTL的表达在不同时间点在肝脏，脾脏，头部肾脏和血液中表达上调。这些结果暗示该CTL基因可能是病原体刺激下黄yellow鱼先天免疫系统中重要的病原体模式识别分子。