NIDOGEN - A NEW, SELF-AGGREGATING BASEMENT-MEMBRANE PROTEIN
NIDOGEN - A NEW, SELF-AGGREGATING BASEMENT-MEMBRANE PROTEIN
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DOI：
10.1111/j.1432-1033.1983.tb07849.x
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
WICK, G
中科院分区：
文献类型：
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作者：
TIMPL, R;DZIADEK, M;WICK, G
巢蛋白是从小鼠肿瘤基底膜中纯化的，其中它占总蛋白的2-3%。分离得到2种形式（A和B）的单体（MW = 80，000），每种形式均由折叠成连接到小尾的球状头部的单一多肽链组成。在一些浸提液中观察到单体的B型能够聚集成巢状结构（MW > 250，000）。巢蛋白的氨基酸组成与其它基底膜蛋白不同。它包含. apprx。10%碳水化合物，N-连接和O-连接寡糖链比例相似。等电聚焦显示巢蛋白的异质性有限，pI在6.5-7之间。单体巢蛋白不能与其他基底膜成分和肝素相互作用。聚集可以诱导有限的蛋白水解和逆转洗涤剂或高盐浓度。连同观察到大部分巢蛋白仅在破坏胶原基质后才能溶解，数据表明巢蛋白的聚集反映了参与基质组装的活性。针对巢蛋白产生的特异性抗体没有区分蛋白质的单体和聚集形式，但表明该片段是抗原性缺陷的。这些抗体不与IV型胶原、层粘连蛋白、巢蛋白和硫酸肝素蛋白聚糖发生交叉反应。免疫荧光染色和吸收研究表明，巢蛋白是一个真正的基底膜的共同组成部分。较大形式的巢蛋白（MW约为100，000和150，000）在Reichert膜的器官培养物中发现，这表明它是以前体形式合成的。
Nidogen was purified from a mouse tumor basement membrane where it accounted for 2-3% of the total proteins. It was isolated as 2 forms (A and B) of a monomer (MW = 80,000) each consisting of a single polypeptide chain folded into a globular head connected to a small tail. The B form of the monomer was capable of aggregating into a nest-like structure (MW > 250,000) was observed in some of the extracts. The amino acid composition of nidogen was different than that of other basement membrane proteins. It contained .apprx. 10% carbohydrate, with N-linked and O-linked oligosaccharide chains in similar proportions. Isoelectrofocusing demonstrated a limited heterogeneity of nidogen with pI in the range 6.5-7. Monomeric nidogen failed to interact with other basement membrane components and heparin. Aggregation could be induced by limited proteolysis and was reversed by detergents or high salt concentrations. Together with the observation that most of the nidogen could be solubilized only after destroying the collagenous matrix, the data indicate that aggregation of nidogen reflects an activity involved in matrix assembly. Specific antibodies raised against nidogen did not distiguish between the monomeric and aggregated form of the protein but showed that the fragment was antigenically deficient. These antibodies did not cross-react with collagen type IV, laminin, entactin and heparin sulfate proteoglycan. Immunofluorescence staining and absorption studies demonstrated that nidogen is a common component of authentic basement membranes. Larger forms of nidogen (MW .apprx. 100,000 and 150,000) were found in organ cultures of Reichert''s membrane suggesting that it is synthesized in precursor forms.