DISRUPTION OF THE ACTIN CYTOSKELETON IN YEAST CAPPING PROTEIN MUTANTS
DISRUPTION OF THE ACTIN CYTOSKELETON IN YEAST CAPPING PROTEIN MUTANTS
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DOI：
10.1038/344352a0
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发表时间：
1990-03-22
期刊：
影响因子：
64.8
通讯作者：
COOPER, JA
中科院分区：
文献类型：
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作者：
AMATRUDA, JF;CANNON, JF;COOPER, JA
CAPPING蛋白在体外控制肌动蛋白亚基向肌动蛋白丝倒刺末端的添加，并使肌动蛋白聚合成核。到目前为止，已在所有检查的真核细胞中鉴定出加帽蛋白;它是一种异二聚体，具有相对分子质量为32，000 - 36，000（α亚基）和28，000 - 32，000（β亚基）的亚基1，2。在骨骼肌中，加帽蛋白（CapZ）可能在Z线3处结合肌动蛋白丝的倒刺末端。这种蛋白质在非肌肉细胞中的活性尚不清楚。本文报道了酿酒酵母中编码加帽蛋白β亚基的单基因CAP 2的特性。在酵母细胞中，CAP 2基因被插入或缺失破坏，肌动蛋白分布异常，包括肌动蛋白电缆的丢失。突变体细胞是圆的和大的，具有异质性的大小分布，并且，虽然可行，生长比同类野生型细胞更慢。几丁质是一种细胞壁成分，仅限于野生型芽殖酵母的母芽连接处，在突变体的整个母细胞表面上发现。CAP 2破坏的表型与酵母肌动蛋白基因ACT 1的温度敏感突变相似（参考文献4），表明加帽蛋白调节体内肌动蛋白丝的分布。
CAPPING protein controls the addition of actin subunits to the barbed end of actin filaments and nucleates actin polymerizationin vitro. Capping protein has been identified in all eukaryotic cells examined so far; it is a heterodimer with subunits of relative molecular masses 32,000–36,000 (α-subunit) and 28,000–32,000 (β-subunit)1,2. In skeletal muscle, capping protein (CapZ) probably binds the barbed ends of actin filaments at the Z line3. Thein vivorole of this protein in non-muscle cells is not known. We report here the characterization ofCAP2, the single gene encoding the β-subunit of capping protein inSaccharomyces cerevisiae. Yeast cells in which theCAP2gene was disrupted by an insertion or a deletion had an abnormal actin distribution, including the loss of actin cables. The mutant cells were round and large, with a heterogeneous size distribution, and, although viable, grew more slowly than congenic wild-type cells. Chitin, a cell wall component restricted to the mother–bud junction in wild-type budding yeast, was found on the entire mother cell surface in the mutants. The phenotype ofCAP2disruption resembled that of temperature-sensitive mutations in the yeast actin geneACT1(ref. 4), indicating that capping protein regulates actin-filament distributionin vivo.