Interactions of actin, myosin, and an actin-binding protein of chronic myelogenous leukemia leukocytes.
Interactions of actin, myosin, and an actin-binding protein of chronic myelogenous leukemia leukocytes.
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慢性粒细胞白血病白细胞的肌动蛋白、肌球蛋白和肌动蛋白结合蛋白的相互作用。
DOI：
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发表时间：
1976
影响因子：
15.9
通讯作者：
T. Stossel
中科院分区：
文献类型：
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作者：
L. Boxer;T. Stossel
从慢性粒细胞白血病（CML）白细胞中纯化肌动蛋白、肌球蛋白和一种高分子量肌动蛋白结合蛋白。CML白细胞肌动蛋白类似于骨骼肌和其他细胞质肌动蛋白的亚基分子量，其能力，在盐的存在下，并激活Mg 2 +-ATP酶活性的兔骨骼肌肌球蛋白。CML白细胞肌球蛋白与其他脊椎动物细胞质肌球蛋白相似，具有重链和两个轻亚基。然而，其表观重链分子量和Stokes半径表明其在纯化过程中发生了降解。纯化的CML白细胞肌球蛋白的平均比EDTA-和Ca ~（2+）-激活的ATP酶活性分别为125和151 nmol Pi释放/mg蛋白/min，比Mg ~（2+）-ATP酶活性较低。CML肌球蛋白的Mg ~（2+）-ATP酶活性被F-actin激活后提高了200倍，但比活性较低。CML白细胞肌球蛋白，像其他脊椎动物的细胞质肌球蛋白，在0.1 M KCl溶液中形成细丝。还原和变性的CML白细胞肌动蛋白结合蛋白有一个单一的高分子量亚基，像最近描述的兔肺巨噬细胞肌动蛋白结合蛋白，促进肌动蛋白的聚合和凝胶化。用含有Mg 2 +-ATP、二硫苏糖醇和EDTA（pH 7.0）的冰冷0.34 M蔗糖溶液制备CML白细胞的细胞质提取物，当加热至25 ℃时发生快速凝胶化。最初，凝胶可以通过冷却至冰浴温度而液化。随着时间的推移，温热的细胞质提取物凝胶收缩（“收缩”）成聚集体。结果表明，CML白细胞肌动蛋白结合蛋白促进了细胞质提取物中肌动蛋白的温度依赖性凝胶化，并且CML白细胞肌球蛋白参与了肌动蛋白凝胶的收缩：（a）细胞质提取物凝胶最初含有肌动蛋白作为其主要多肽成分，并与缠结的细丝一致;（B）由大量肌球蛋白以及肌动蛋白所包含的细胞质提取物凝胶的收缩聚集体;（c）纯化的肌动蛋白结合蛋白经历温度依赖性，可逆聚集，并引起低浓度纯化的肌肉或CML白细胞肌动蛋白在蔗糖溶液中胶凝;（d）由纯化的肌动蛋白加上纯化的肌动蛋白形成的凝胶。结合蛋白在存在纯化的CML白细胞肌球蛋白的情况下缓慢收缩，但在不存在纯化的CML白细胞肌球蛋白的情况下不收缩;（e）针对纯化的CML白细胞肌动蛋白的兔抗血清结合蛋白，但不针对纯化的CML白细胞肌球蛋白抑制热CML白细胞提取物的凝胶化。抗CML白细胞肌球蛋白的抗血清对CML白细胞提取物的凝胶化没有影响，但部分减少了CML白细胞提取物凝胶和纯化的CML白细胞肌动蛋白结合蛋白加兔骨骼肌肌动蛋白形成的凝胶的收缩。
Actin, myosin, and a high molecular weight actin-binding protein were purified from chronic myelogenous leukemia (CML) leukocytes. CML leukocyte actin resembled skeletal muscle and other cytoplasmic actins by its subunit molecular weight, by its ability to polymerize in the presence of salts, and to activate the Mg2+-ATPase activity of rabbit skeletal muscle myosin. CML leukocyte myosin was similar to other vertebrate cytoplasmic myosins in having heavy chains and two light subunits. However, its apparent heavy-chain molecular weight and Stokes radius suggested that it was variably degraded during purification. Purified CML leukocyte myosin had average specific EDTA- AND Ca2+-activated ATPase activities of 125 and 151 nmol Pi released/mg protein per min, respectively and low specific Mg2+-ATPase activity. The Mg2+-ATPase activity of CML myosin was increased 200-fold by rabbit skeletal muscle F-actin, but the specific activity relative to that of actin-activated rabbit skeletal muscle myosin was low. CML leukocyte myosin, like other vertebrate cytoplasmic myosins, formed filaments in 0.1 M KCl solutions. Reduced and denatured CML leukocyte-actin-binding protein had a single high molecular weight subunit like a recently described actin-binding protein of rabbit pulmonary macrophages which promotes the polymerization and gelation of actin. Cytoplasmic extracts of CML leukocytes prepared with ice-cold 0.34-M sucrose solutions containing Mg2+-ATP, dithiothreitol, and EDTA at pH 7.0 underwent rapid gelation when warmed to 25 degrees C. Initially, the gel could be liquified by cooling to ice-bath temperature. With time, warmed cytoplasmic extract gels shrunk ("contracted") into aggregates. The following findings indicated that CML leukocyte actin-binding protein promoted the temperature-dependent gelation of actin in the cytoplasmic extracts and that CML leukocyte myosin was involved in the contraction of the actin gels: (a) Cytoplasmic extract gels initially contained actin as their major polypeptide component and consistent of tangled thin filaments; (b) Contracted aggregates of cytoplasmic extract gels contained by large quantities of myosin as well as actin; (c) Purified actin-binding protein underwent a temperature-dependent, reversible aggregation and caused low concentrations of purified muscle or CML leukocyte actins to gel in sucrose solutions; (d) The gels formed from purified actin plus purified actin-binding protein slowly contracted in the presence but not in the absence of purified CML leukocyte myosin; (e) Rabbit antiserum against purified CML leukocyte actin-binding protein but not against purified CML leukocyte myosin inhibited the gelation of warmed CML leukocyte extracts. Antiserum against CML leukocyte myosin had no effect on the gelation of CML leukocyte extracts but partially curtailed the contraction of the CML leukocyte extract gels and of gels formed from purified CML leukocyte actin-binding protein plus rabbit skeletal muscle actin.