Yeast actin cytoskeleton mutants accumulate a new class of Golgi-derived secretory vesicle
Yeast actin cytoskeleton mutants accumulate a new class of Golgi-derived secretory vesicle
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DOI：
10.1091/mbc.8.8.1481
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发表时间：
1997-08-01
影响因子：
3.3
通讯作者：
Botstein, D
中科院分区：
文献类型：
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作者：
Mulholland, J;Wesp, A;Botstein, D
许多酵母肌动蛋白细胞骨架突变体积累大的分泌囊泡，并表现出与极化生长缺陷相一致的表型。这与肌动蛋白的极化组织一起，表明了肌动蛋白细胞骨架在晚期分泌囊泡向质膜的载体运输中的作用。通过使用超微结构和生物化学分析，我们已经表征了SLA 2基因（也称为END 4基因）突变所表现出的缺陷，该基因先前被发现影响肌动蛋白细胞骨架的组织和酵母中的内吞作用。在sla 2突变体中发现了细胞壁形态、积累的囊泡和蛋白质分泌动力学的缺陷，这些缺陷与act 1突变体中发现的缺陷相似。在sla 2和act 1突变体中积累的囊泡与针对小的GT3 Ypt 1 p的抗体具有免疫反应性，但与针对在经典的“晚期"分泌囊泡上发现的同源Sec 4p的抗体不具有免疫反应性。相反，晚作用分泌突变体sec 1 -1和sec 6 -4显示积累抗Sec 4p阳性分泌囊泡以及与针对Ypt 1 p的抗体免疫反应的囊泡。晚sec突变体sec 4 -8也被证明积累Ypt 1 p-含有囊泡，并表现出缺陷的肌动蛋白细胞骨架组织。这些结果表明存在至少两类形态相似的晚期分泌囊泡（分别与Ypt 1 p（+）和Sec 4p（+）相关），其中一类似乎在肌动蛋白细胞骨架紊乱时积累。
Many yeast actin cytoskeleton mutants accumulate large secretory vesicles and exhibit phenotypes consistent with defects in polarized growth. This, together with actin's polarized organization, has suggested a role for the actin cytoskeleton in the vectorial transport of late secretory vesicles to the plasma membrane. By using ultrastructural and biochemical analysis, we have characterized defects manifested by mutations in the SLA2 gene (also known as the END4 gene), previously found to affect both the organization of the actin cytoskeleton and endocytosis in yeast. Defects in cell wall morphology, accumulated vesicles, and protein secretion kinetics were found in sla2 mutants similar to defects found in act1 mutants. Vesicles that accumulate in the sla2 and act1 mutants are immunoreactive with antibodies directed against the small GTPase Ypt1p but not with antibodies directed against the homologous Sec4p found on classical ''late'' secretory vesicles. In contrast, the late-acting secretory mutants sec1-1 and sec6-4 are shown to accumulate anti-Sec4p-positive secretory vesicles as well as vesicles that are immunoreactive with antibodies directed against Ypt1p. The late sec mutant sec4-8 is also shown to accumulate Ypt1p-containing vesicles and to exhibit defects in actin cytoskeleton organization. These results indicate the existence of at least two classes of morphologically similar, late secretory vesicles (associated with Ypt1p(+) and Sec4p(+), respectively), one of which appears to accumulate when the actin cytoskeleton is disorganized.