The homologue of mannose-binding lectin in the carp family Cyprinidae is expressed at high level in spleen, and the deduced primary structure predicts affinity for galactose
The homologue of mannose-binding lectin in the carp family Cyprinidae is expressed at high level in spleen, and the deduced primary structure predicts affinity for galactose
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DOI：
10.1007/s002510000260
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发表时间：
2000
期刊：
影响因子：
3.2
通讯作者：
L. Vitved;U. Holmskov;C. Koch;B. Teisner;S. Hansen;J. Salomonsen;K. Skjødt
中科院分区：
文献类型：
--
作者：
L. Vitved;U. Holmskov;C. Koch;B. Teisner;S. Hansen;J. Salomonsen;K. Skjødt
甘露糖结合凝集素(MBL)作为补体系统的激活剂和与微生物上特定碳水化合物结构结合后的调理素参与天然免疫系统。我们从鲤科鲤科的三个成员，斑马鱼Danio rerio，金鱼Carassius auratus和鲤鱼CarpCyprinus Carpio中分离并鉴定了编码MBL同源物的cDNA转录本。鲤鱼和斑马鱼的转录本含有两个多聚腺苷酸化位点，对鲤鱼组织中的mRNA进行RT-PCR分析表明，鲤鱼转录本在脾中的表达最显著。推测的成熟蛋白含有2 2 8或2 33个氨基酸，N末端含有一个保守的半胱氨酸，预计可形成链间二硫键桥，两个甘氨酸残基之间的胶原区被4个氨基酸打断，颈区预测形成α螺旋卷曲结构，以及C端糖识别结构域。CRD中的几个结构上重要的残基是保守的，但已知与碳水化合物配体的钙离子和羟基相互作用的残基是不同的。氨基酸基序EPN对甘露糖的专一性很重要，在鲤科同源物中是QPD，这表明半乳糖是专一性的。推导的氨基酸序列在鲤鱼和金鱼之间有90%以上的同源性，在这两个物种与斑马鱼之间分别有68%和65%的同源性。与鸟类和哺乳动物的同源性在28%到33%之间。
Mannose-binding lectin (MBL) participates in the innate immune system as an activator of the complement system and as an opsonin after binding to certain carbohydrate structures on microorganisms. We isolated and characterized cDNA transcripts encoding an MBL homologue from three members of the carp family Cyprinidae, the zebrafishDanio rerio, the goldfishCarassius auratus, and the carpCyprinus carpio. The carp and zebrafish transcripts contain two polyadenylation sites and RT-PCR on mRNA from carp tissues revealed the carp transcript to be most prominently expressed in the spleen. The deduced mature proteins contain 228 or 233 amino acids with a short N-terminal segment containing a single conserved cysteine expected to form interchain disulfide bridges, a collagen domain interrupted by four amino acids between two glycine residues, a neck region predicted to form an α-helical coiled-coil structure, and a C-terminal carbohydrate recognition domain (CRD). Several of the structurally important residues in the CRD are conserved, but the residues known to interact with the calcium ion and hydroxyl groups of the carbohydrate ligand are different. The amino acid motif EPN, important for mannose specificity, was QPD in the Cyprinidae homologue, suggesting specificity for galactose instead. The identity between the deduced amino acid sequences is more than 90% between the carp and the goldfish and 68% and 65% between these two species, respectively, and the zebrafish. The identity with bird and mammalian MBLs ranges from 28 to 33%.