AFFINITY OF ALPHA-ACTININ FOR ACTIN DETERMINES THE STRUCTURE AND MECHANICAL-PROPERTIES OF ACTIN FILAMENT GELS
AFFINITY OF ALPHA-ACTININ FOR ACTIN DETERMINES THE STRUCTURE AND MECHANICAL-PROPERTIES OF ACTIN FILAMENT GELS
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DOI：
10.1016/s0006-3495(93)81059-2
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发表时间：
1993-07-01
影响因子：
3.4
通讯作者：
POLLARD, TD
中科院分区：
文献类型：
--
作者：
WACHSSTOCK, DH;SCHWARZ, WH;POLLARD, TD
交联肌动蛋白丝的蛋白质既可以形成平行的纤维束，也可以形成由单个纤维组成的各向同性网络。我们已经发现，肌动蛋白丝与从卡氏阿米巴或鸡平滑肌中纯化的α-辅肌动蛋白的混合物可以根据其浓度形成束或各向同性网络。低浓度的α-辅肌动蛋白和肌动蛋白丝形成的网络在电子显微镜下与单独的肌动蛋白凝胶难以区分。高浓度的α-辅肌动蛋白和肌动蛋白丝形成束。成束的阈值取决于α-辅肌动蛋白对肌动蛋白的亲和力。阿米巴α-辅肌动蛋白与肌动蛋白丝的复合物的K（d）为4.7 μ M，成束阈值为0.1 μ M;鸡平滑肌的K（d）为0.6 μ M，成束阈值为1 μ M。交联肌动蛋白丝的各向同性网络的物理性质与束的凝胶非常不同：网络表现得像固体，因为每个肌动蛋白丝都是包含所有丝的单一结构的一部分。纤维束的行为更像是一种非常粘稠的流体，因为每一束纤维虽然很长很硬，但可以滑过其他纤维束。我们已经开发了一个计算机模型，预测捆绑阈值的基础上四个变量：肌动蛋白丝的长度，α-辅肌动蛋白的亲和力，以及肌动蛋白和α-辅肌动蛋白的浓度。
Proteins that cross-link actin filaments can either form bundles of parallel filaments or isotropic networks of individual filaments. We have found that mixtures of actin filaments with alpha-actinin purified from either Acanthamoeba castellanii or chicken smooth muscle can form bundles or isotropic networks depending on their concentration. Low concentrations of alpha-actinin and actin filaments form networks indistinguishable in electron micrographs from gels of actin alone. Higher concentrations of alpha-actinin and actin filaments form bundles. The threshold for bundling depends on the affinity of the alpha-actinin for actin. The complex of Acanthamoeba alpha-actinin with actin filaments has a K(d) of 4.7 muM and a bundling threshold of 0.1 muM; chicken smooth muscle has a K(d) of 0.6 muM and a bundling threshold of 1 muM. The physical properties of isotropic networks of cross-linked actin filaments are very different from a gel of bundles: the network behaves like a solid because each actin filament is part of a single structure that encompasses all the filaments. Bundles of filaments behave more like a very viscous fluid because each bundle, while very long and stiff, can slip past other bundles. We have developed a computer model that predicts the bundling threshold based on four variables: the length of the actin filaments, the affinity of the alpha-actinin for actin, and the concentrations of actin and alpha-actinin.