STRUCTURE OF F-ACTIN AND OF ACTIN FILAMENTS ISOLATED FROM MUSCLE
STRUCTURE OF F-ACTIN AND OF ACTIN FILAMENTS ISOLATED FROM MUSCLE
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DOI：
10.1016/s0022-2836(63)80081-9
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发表时间：
1963-01-01
影响因子：
5.6
通讯作者：
LOWY, J
中科院分区：
文献类型：
--
作者：
HANSON, J;LOWY, J
收缩装置的细丝已从多种平滑肌和横纹肌中分离出来，并在电子显微镜的负染色制剂中进行检查。在所有情况下，都存在与 F-肌动蛋白制剂中的细丝无法区分的细丝。该细丝由两条螺旋缠绕的股线组成，该股线由看起来相似且近似球形的亚基组成。亚基的排列对应于 Selby 和 Bear (1956) 根据完整干燥肌肉的中角 X 射线衍射图推断出的肌动蛋白可能结构之一的散射中心的排列。每圈螺旋的球状亚基数量（如果是整体）为 13（参见根据衍射数据提出的模型中的 13 或 15）。沿每条链的亚基间距为 56.5 A（参见衍射数据提出的模型中的 55 A）。两根加捻股线的交叉点沿细丝以 349 A 的间隔间隔开（参见根据衍射数据提出的模型中的 351 A 或 406 A）。丝的总直径约为80埃。以兔子骨骼肌为例，结果表明该结果与该肌肉中肌动蛋白的数量一致。有充分的证据表明，电子显微镜中看到的每个球状亚基都代表一个肌动蛋白单体。肌动蛋白本身的结构不能解释（i）在电子显微镜中在原纤维的 I-物质中观察到的大约 400 A 的轴向周期性，或（ii）在完整肌肉的轴向衍射图中观察到的大约 400 A 的反射。建议 (i) 和 (ii) 都可能是由于肌动蛋白与其他物质（可能是原肌球蛋白 B）的结合所致。
The filaments of the contractile apparatus have been isolated from a wide variety of smooth and striated muscles and examined in negatively-stained preparations in the electron microscope. In all cases there are thin filaments which are indistinguishable from the filaments in F-actin preparations. The filament consists of two helically-wound strands composed of subunits which appear to be alike and approximately spherical. The arrangement of the subunits corresponds to that of the scattering centres in one of the possible structures for actin deduced by Selby and Bear (1956) from the moderate-angle X-ray diffraction pattern of intact dried muscle. The number of globular subunits per turn of the helix (if integral) is 13 (cf . either 13 or 15 in the models proposed from diffraction data). The spacing of the subunits along each strand is 56.5 A (cf. 55 A in the models proposed from diffraction data). The cross-oyer points of the two twisted strands are spaced at intervals of 349 A along the filament (cf. either 351 A or 406 A in the models proposed from diffraction data). The overall diameter of the filament is about 80 A It is shown in the case of rabbit skeletal muscle that this result is consistent with the quantity of actin in that muscle. There is good evidence that each of the globular subunits seen in the electron microscope represents one actin monomer. The structure of actin alone does not account for (i) the approximately 400 A axial periodicity observed in the I-substance of fibrils in the electron microscope, or (ii) the reflection at about 400 A observed in the axial diffraction pattern of intact muscle. It is suggested that both (i) and (ii) could be due to the combination of actin with other material, possibly tropomyosin B.