Cloning of gp-340, a putative opsonin receptor for lung surfactant protein D
Cloning of gp-340, a putative opsonin receptor for lung surfactant protein D
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DOI：
10.1073/pnas.96.19.10794
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发表时间：
1999-09-14
影响因子：
11.1
通讯作者：
Skjodt, K
中科院分区：
文献类型：
--
作者：
Holmskov, U;Mollenhauer, J;Skjodt, K
表面活性蛋白D（SP-D）是一种低聚C型凝集素，其通过结合微生物表面碳水化合物来促进吞噬作用。一种340-kD的糖蛋白（gp-340）已被证明在钙存在下结合SP-D，但不依赖于碳水化合物识别。该蛋白以可溶形式存在，并与肺泡巨噬细胞的膜结合。gp-340的一级结构已通过分子克隆建立，其产生了编码2，413个氨基酸。结构域组织具有13个清道夫受体富含半胱氨酸（SRCR）结构域，每个结构域由SRCR散布结构域分隔，除了SRCR 4和5，它们是连续的。在13个SRCR结构域之后是两个C1 r/C1 s Uegf Bmp 1结构域，其中间被第14个SRCR结构域和一个透明质酸结构域隔开，gp-340似乎是DMBT 1的可变剪接形式。逆转录-PCR分析表明，gp-340的主要合成部位是肺、气管、唾液腺、小肠和胃。免疫组化显示肺泡和其他组织巨噬细胞中gp-340的强染色。巨噬细胞膜的免疫染色是均匀的或局灶性的方式，建议加盖，而其他巨噬细胞内的吞噬体/吞噬溶酶体室显示出强烈的细胞内染色。在某些巨噬细胞中，SP-D和gp-340位于同一细胞室中，免疫反应性gp-340也见于小肠上皮细胞和唾液腺导管中。gp-340在巨噬细胞中的分布与作为SP-D调理素受体的作用相容。
Surfactant protein D (SP-D) is an oligomeric C type lectin that promotes phagocytosis by binding to microbial surface carbohydrates. A 340-kD glycoprotein (gp-340) has been shown to bind SP-D in the presence of calcium but does so independently of carbohydrate recognition, This protein exists both in a soluble form and in association with the membranes of alveolar macrophages, The primary structure of gp-340 has been established by molecular cloning, which yielded a 7,686-bp cDNA sequence encoding a polypeptide chain of 2,413 amino acids. The domain organization features 13 scavenger receptor cysteine-rich (SRCR) domains, each separated by an SRCR-interspersed domain, except for SRCRs 4 and 5, which are contiguous. The 13 SRCR domains are followed by two C1r/C1s Uegf Bmp1 domains separated by a 14th SRCR domain and a zona pellucida domain, gp-340 seems to be an alternative spliced form of DMBT1. Reverse transcription-PCR analysis showed that the main sites of synthesis of gp-340 are lung, trachea, salivary gland,small intestine, and stomach. Immunohistochemistry revealed strong staining for gp-340 in alveolar and other tissue macrophages. Immunostaining of the macrophage membrane was either uniform or focal in a way that suggested capping, whereas other macrophages showed strong intracellular staining within the phagosome/phagolysosome compartments. In some macrophages, SP-D and gp-340 were located in the same cellular compartment, Immunoreactive gp-340 was also found in epithelial cells of the small intestine and in the ducts of salivary glands. The distribution of gp-340 in macrophages is compatible with a role as an opsonin receptor for SP-D.