Gap junction structures. V. Structural chemistry inferred from X-ray diffraction measurements on sucrose accessibility and trypsin susceptibility.
Gap junction structures. V. Structural chemistry inferred from X-ray diffraction measurements on sucrose accessibility and trypsin susceptibility.
复制标题
间隙连接结构。
DOI：
10.1016/0022-2836(84)90331-0
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发表时间：
1984
影响因子：
5.6
通讯作者：
Goodenough,DA
中科院分区：
文献类型：
--
作者：
Makowski,L;Caspar,DL;Phillips,WC;Goodenough,DA
从小鼠肝脏分离出部分取向的缝隙连接样品，悬浮在不同浓度和不同电子密度的蔗糖溶液中，记录了X射线衍射图。对这些衍射图的分析表明，蔗糖被排除在结晶格的6倍旋转轴上，长度约为100？这表明在这些制剂中，结的水通道处于闭合的高阻状态。连接处蔗糖可达空间的作图表明，通道入口在细胞质一侧的横截面积可能比跨膜通道的面积大5倍。蔗糖不会沿着通道穿透超过20？的膜。显然，水通道的大部分长度为8到10？半径，在距离缝隙中心约50？的地方被一个小特征缩小或堵塞。缝隙连接蛋白与细胞质表面的脂极性头部基团之间存在着非常密切的相互作用。在这个区域，蛋白质插入到两个极头基团之间。这些结果表明，缝隙连接蛋白可能具有功能性的双域结构。一个相对分子质量约为15,000的结构域跨越一个双分子层和一半的间隙，基本上包含在距6倍轴25？的半径内。第二个结构域较小，占据缝隙连接膜的细胞质表面。胰酶消化可从连接蛋白的细胞质表面区中去除约4000mrr。大多数易受胰酶消化的物质位于离6倍轴28°以上的位置。
X-ray diffraction patterns have been recorded from partially oriented specimens of gap junctions isolated from mouse liver and suspended in sucrose solutions of different concentration and thus of different electron density. Analysis of these diffraction patterns has shown that sucrose is excluded from the 6-fold rotation axis of the junction lattice for a length of about 100 Å. This indicates that the aqueous channel of the junctions is in the closed, high resistance state in these preparations. Mapping of the sucrose-accessible space in the junction indicates that the cross-sectional area of the channel entrance on the cytoplasmic side of the membrane could be up to five times larger than the area of the transmembrane channel. Sucrose does not penetrate more than 20 Å into the membrane along the channel. Apparently the aqueous channel, 8 to 10 Å in radius for most of its length, is narrowed or blocked by a small feature about 50 Å from the center of the gap. Very close interactions exist between the gap junction protein and the lipid polar head groups on the cytoplasmic surface of the membrane. In this region, the protein intercalates between the polar head groups. These results suggest that the gap junction protein may have a functional two-domain structure. One domain, with a molecular weight of about 15,000, spans one bilayer and half of the gap and is contained largely within a radius of 25 Å from the 6-fold axis. The second domain is smaller and occupies the cytoplasmic surface of the gap junction membrane. Trypsin digestion removes about 4000Mrmrfrom the cytoplasmic surface domain of the junction protein. Most of the material susceptible to trypsin digestion is located more than 28 å from the 6-fold axis.
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作者：
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影响因子：
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作者：
MorrissJr,FH;Moore,M;Weisbrodt,NW;West,MS
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影响因子：
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作者：
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通讯作者：
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DOI：
--
发表时间：
1989
期刊：
影响因子：
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作者：
R. Amarnath;C. Berseth;J. Malagelada;J. Perrault;T. Abell;A. D. Hoffman
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