SHAPES, DOMAIN ORGANIZATIONS AND FLEXIBILITY OF LAMININ AND FIBRONECTIN, 2 MULTIFUNCTIONAL PROTEINS OF THE EXTRACELLULAR-MATRIX
SHAPES, DOMAIN ORGANIZATIONS AND FLEXIBILITY OF LAMININ AND FIBRONECTIN, 2 MULTIFUNCTIONAL PROTEINS OF THE EXTRACELLULAR-MATRIX
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DOI：
10.1016/0022-2836(81)90326-0
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发表时间：
1981-01-01
影响因子：
5.6
通讯作者：
TIMPL, R
中科院分区：
文献类型：
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作者：
ENGEL, J;ODERMATT, E;TIMPL, R
用旋转阴影法和阴性染色法对小鼠肿瘤（EHS肉瘤）基底膜的层粘连蛋白和人血浆的纤维连接蛋白进行了电镜观察，对未染色样品进行了透射扫描电镜观察。层粘连蛋白是由一条长臂（77 nm）和三条明显相同的短臂（36 nm）组成的刚性、不对称交叉结构。杆状臂（直径约2纳米）以球状单位（直径5-7纳米）终止。在短臂末端单位附近发现了额外的小球体。层粘连蛋白的一个大的抗胃蛋白酶片段呈刚性结构，具有3条臂（长26 nm，优选角90度），可能代表层粘连蛋白3条短臂的一部分。纤维连接蛋白可以可视化为2条相同的链（长61 nm，直径约2 nm），没有显示明显的球状单位。这些链很可能是由一端相互连接的单肽链组成的，形成一个约70度的固定角。EM还表明层粘连蛋白和纤维连接蛋白臂的柔韧性有限，与原肌球蛋白或DNA的硬度相当。层粘连蛋白、层粘连蛋白片段和纤维连接蛋白的形状和尺寸的EM图像与特定的分子量和溶液中测定的流体动力学性质一致。纤维连接蛋白臂上有3个不同的区域发生优先弯曲。这些位点显然对应于先前在生化研究中发现的连接更紧凑结构域的柔性片段。层粘连蛋白臂部未见优先弯曲位点。虽然层粘连蛋白和纤维连接蛋白具有一些相似的生物活性（结合细胞、胶原蛋白、糖胺聚糖），但相应的功能域在2个分子中排列不同。
Laminin from a mouse tumor (EHS sarcoma) basement membrane and fibronectin from human blood plasma were examined by EM using rotary shadowing and negative staining and by transmission scanning electron microscopy of unstained samples. Laminin was visualized as a rigid, asymmetric cross consisting of a long (77 nm) and 3 apparently identical short (36 nm) arms. The rod-like arms (diameter about 2 nm) terminated in globular units (diameter 5-7 nm). Additional globules were found near the terminal units in the short arms. A large pepsin-resistant fragment of laminin appeared as a rigid structure with 3 arms (length 26 nm, preferred angle 90.degree.), which presumably represented parts of the 3 short arms of laminin. Fibronectin could be visualized as 2 identical strands (length 61 nm, diameter about 2 nm), which did not reveal distinct globular units. These strands very likely comprised single peptide chains connected to each other at 1 end, enclosing a fixed angle of about 70.degree.. EM also indicated a limited flexibility of the arms of both laminin and fibronectin, comparable to the stiffness of tropomyosin or DNA. The EM images of the shapes and dimensions of laminin, of fragments of laminin, and of fibronectin are consistent with the specific MW and with the hydrodynamic properties determined in solution. The arms of fibronectin showed 3 distinct regions at which preferential bending occurred. These sites apparently correspond to flexible segments connecting more compact domains previously identified in biochemical studies. No sites of preferential bending were visible in the arms of laminin. Although laminin and fibronectin have some similar biological activities (binding of cells, collagen, glycosaminoglycans), the corresponding functional domains are differently arranged in the 2 molecules.