CHARACTERIZATION OF MURINE MANNOSE-BINDING PROTEIN GENES MBL1 AND MBL2 REVEALS FEATURES COMMON TO OTHER COLLECTIN GENES
CHARACTERIZATION OF MURINE MANNOSE-BINDING PROTEIN GENES MBL1 AND MBL2 REVEALS FEATURES COMMON TO OTHER COLLECTIN GENES
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DOI：
10.1007/bf00303252
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发表时间：
1995-02-01
期刊：
影响因子：
2.5
通讯作者：
SASTRY, KN
中科院分区：
文献类型：
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作者：
SASTRY, R;WANG, JS;SASTRY, KN
甘露糖结合蛋白（MBP）是胶原凝集素家族的一员，被认为在一线宿主防御中起重要作用。本研究分离了小鼠MBP的两个编码基因mbl1和Mb12，并研究了它们的外显子-内含子结构，以了解它们与人类单基因（MBL）和两个大鼠MBP基因的进化关系。小鼠Mbl1和Mbl2分别有5个和6个外显子。小鼠Mbl基因的结构与大鼠和人的MBP基因相似，并与其他收集基因具有同源性，整个碳水化合物识别结构域编码在单个外显子中，所有内含子都处于phase 1。小鼠Mbl1编码的MBP在第一个编码外显子中有三个半胱氨酸，与大鼠Mbl1和人MBL一样，具有更高程度的多聚性，并且在缺乏抗体或C1q的情况下具有明显的修复补体的能力。然而，其他外显子的结构特征，即第一个编码外显子的胶原结构域较大（Mbl2为64 bp，而Mbl1为46 bp）和编码三聚结构域的外显子较小（Mbl2为69 bp，而Mbl1为75 bp），表明人类单个MBL基因与啮齿动物Mbl2而非啮齿动物Mbl1密切相关。本研究结果表明，与另一种收集基因-牛表面活性蛋白d -在与人类分化后在牛科中复制的进化相反，MBP基因很可能在人类与啮齿动物分化之前复制，并且人类与Mbl1的同源基因可能在进化过程中丢失。
Mannose-binding protein (MBP) is a member of a family of collagenous lectins (collectins), which are believed to play an important role in first-line host defense. In this study, the two genes encoding MBP in mice -Mbl1 and Mb12- have been isolated and their exon-intron structure studied to understand their evolutionary relationship to the single human (MBL) and the two rat MBP genes. Mouse Mbl1 and Mbl2 have five and six exons, respectively. The structure of the mouse Mbl genes is similar to that of the rat and human MBP genes and shows homology to the other collectin genes, with the entire carbohydrate recognition domain being encoded in a single exon and all introns being in phase 1. The MBP encoded by mouse Mbl1 with three cysteines in the first coding exon, like the rat Mbl1 and human MBL, is capable of a higher degree of multimerization and has apparent ability to fix complement in the absence of antibody or C1q. However, the structural features of other exons, that is, the larger size of collagen domain region in the first coding exon (64 bp in Mbl2 vs 46 bp in Mbl1) and the smaller size of the exon encoding the trimerization domain (69 bp in Mbl2 vs 75 bp in Mbl1) reveal that the single human MBL gene is closely related to rodent Mbl2 rather than rodent Mbl1. The findings in this study suggest that in contrast to the evolution of another collectin gene-bovine surfactant protein-D-which duplicated in bovidae after divergence from humans, MBP gene most likely duplicated prior to human-rodent divergence, and that the human homolog to Mbl1 was perhaps lost during evolution.