ELECTRON-MICROSCOPICAL APPROACH TO A STRUCTURAL MODEL OF INTIMA COLLAGEN
ELECTRON-MICROSCOPICAL APPROACH TO A STRUCTURAL MODEL OF INTIMA COLLAGEN
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DOI：
10.1042/bj2110303
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发表时间：
1983-01-01
影响因子：
4.1
通讯作者：
ENGEL, J
中科院分区：
文献类型：
--
作者：
FURTHMAYR, H;WIEDEMANN, H;ENGEL, J
通过EM（旋转阴影和负染色）和分析性超离心法研究内膜胶原。单体单元（Mr [相对分子量] 170，000）由一个105 nm长的三螺旋组成，其一端由一个小球状结构域（Mr约30，000）终止，另一端由一个大球状结构域（Mr约40，000）终止。通过选择性还原链间二硫键产生单体。在还原前，发现了二聚体、四聚体和较大的丝状结构，二聚体是两个单体以反平行方式排列的横向交错聚集体。这产生了一个内部的75 nm长的区域的2个稍微相互缠绕的三重螺旋两侧的大球状域。外部三螺旋片段（长度30纳米）在其末端具有小球状结构域，出现在该结构的两侧。链间二硫键可能位于大结构域附近。只有外节可以被细菌胶原酶降解。在四聚体中，2个二聚体的外部片段共价连接，形成剪刀状结构。在纤维形式中，几个四聚体端对端组装，外段之间有重叠。从EM观察到的尺寸，这些不同形式的分子量和沉降系数进行了计算，并同意通过ultracentrapgation得到的结果。内膜胶原蛋白的独特结构表明其来源于微纤维组分，并且其可以被认为是独特的胶原蛋白，为此提出VI型胶原蛋白的名称。
Intima collagen was studied by EM (rotary shadowing and negative staining) and by analytical ultracentrifugation. The monomeric unit (Mr [relative MW] 170,000) consists of a 105 nm-long triple helix terminated by a small globular domain (Mr about 30,000) at 1 end and a large globular domain (Mr about 40,000) at the other end. The monomer was produced by selective reduction of interchain disulfide bridges. Before reduction, dimers, tetramers and larger filamentous structures were found. Dimers are lateral staggered aggregates of 2 monomers aligned in an anti-parallel fashion. This gives rise to an inner 75 nm-long region of 2 slightly intertwisted triple helices flanked by the large globular domains. The outer triple-helical segments (length 30 nm) with the small globular domains at their ends emerge at both sides of this structure. Interchain disulfide bridges are probably located in the vicinity of the large domains. Only the outer segments could be degraded by bacterial collagenase. In tetramers the outer segments of 2 dimers are covalently linked, forming a scissors-like structure. In the fibrous forms several tetramers are assembled end-to-end with an overlap between the outer segments. The molecular masses and sedimentation coefficients were calculated for these various forms from the EM observed dimensions and agreed with results obtained by ultracentrifugation. The unique structure of intima collagen suggests that it originates from a microfibrillar component and that it can be considered a unique collagenous protein, for which the designation type VI collagen is proposed.