STRUCTURE AND MACROMOLECULAR ORGANIZATION OF TYPE-VI COLLAGEN
STRUCTURE AND MACROMOLECULAR ORGANIZATION OF TYPE-VI COLLAGEN
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DOI：
10.1111/j.1749-6632.1985.tb51154.x
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发表时间：
1985-12-30
影响因子：
5.2
通讯作者：
TIMPL, R
中科院分区：
文献类型：
--
作者：
ENGEL, J;FURTHMAYR, H;TIMPL, R
VI型胶原蛋白是一种大的二硫键蛋白复合物，广泛分布于结缔组织中。组成多肽链（Mr= 110，000 - 140，000）由胶原和非胶原片段组成，当胶原VI被胃蛋白酶溶解时降解为约一半大小的链，并组装成独特的寡聚体模式。如通过电子显微镜所揭示的，三链原聚体由长度为105 nm的三螺旋组成，在每一侧上由相似大小的球状结构域（直径约7 nm）侧接。原聚体通过三螺旋片段的反平行交错排列组装成二聚体。这导致内部区域，75纳米长，两个稍微超螺旋的三重螺旋两侧的球状域。在两侧30纳米长的外部三螺旋段出现，终止于小球。四聚体由横向排列的二聚体形成，二聚体以剪刀状方式与其外部三螺旋片段交叉。在胃蛋白酶处理的胶原VI中发现了相同的结构，除了具有小得多的球状结构域。由培养的成纤维细胞产生的二硫键连接的胶原VI具有与在组织提取物中发现的真正的胶原VI相似的尺寸。较大形式的胶原VI由四聚体通过端对端聚集组装而成，由于外段的重叠，使所有球状结构域靠近在一起。这种排列预测组织中的微纤维结构具有100-110 nm的周期性和5-10 nm的直径。胎盘和主动脉的免疫电子显微镜下使用铁蛋白技术确实发现了与这一建议相一致的结构。胶原VI微纤维的大的侧向聚集体可能另外存在于细胞培养物和组织中（“斑马胶原"、”Luse体”），并且推测通过球状结构域之间的接触来维持。
Collagen VI is a large, disulfide-bonded protein complex which is widely distributed in connective tissue. The constituent polypeptide chains (Mr= 110,000-140,000) consist of collagenous and noncollagenous segments, are degraded to chains of about half the size when collagen VI is solubilized by pepsin, and assemble to a unique pattern of oligomers. As revealed by electron microscopy, the triple-stranded protomer consists of a triple helix 105 nm in length flanked on each side by globular domains of similar size (diameter about 7 nm). Protomers are assembled to dimers by an antiparallel staggered alignment of triple-helical segments. This leads to inner regions, 75 nm in length, of two slightly supercoiled triple helices flanked by globular domains. At both sides 30-nm-long outer triple-helical segments emerge that are terminated by globules. Tetramers are formed from laterally aligned dimers that cross with their outer triple-helical segments in a scissors-like fashion. The same structures, except with much smaller globular domains, are found in pepsin-treated collagen VI. Disulfide-linked collagen VI produced by cultured fibroblasts has a size similar to that of genuine collagen VI found in tissue extracts. Larger forms of collagen VI are assembled from tetramers by end-to-end aggregation which because of an overlap of the outer segments brings all globular domains close together. This arrangement predicts microfibrillar structures in tissues with a periodicity of 100-110 nm and a diameter of 5-10 nm. Structures consistent with this proposal were indeed found by immunoelectron microscopy of placenta and aorta using the ferritin technique. Large, lateral aggregates of collagen VI microfibrils may in addition exist in cell cultures and tissues (" zebra collagen,"" Luse bodies") and are presumably maintained by contacts between globular domains.