Ultrastructural Studies on Actin-like Filament in Mung Bean Mitochondria and Its Potential Functional Significance

我們利用對mitoplast的negative stainning方法，在綠豆線粒體中發現5毫微米似肌動蛋白細絲的存在。由冷凍裂解電子顯微鏡觀察，球狀蛋白質組成的5毫微米似肌動蛋白細絲和粒線體的intramembranous particles共存。冷凍裂解的免疫標記法結果，建議似肌動蛋白細絲附在粒線體內膜protoplasmic內外表面。他們也可能位於外膜下層和基質中。由原位immunolocalization方法，也證實肌動蛋白或似肌動蛋白出現在線粒體基質。有趣的是，一些5毫微米似肌動蛋白細絲經常圍繞在線粒體和它的「芽體」之間。這也許代表一種新發現的由5毫微米似肌動蛋白細絲介入的一種新穎的植物粒線體發芽繁殖的過程。線狀肌動蛋白解聚作用試劑，Latrunculin B處理煙草細胞, 可影響粒線體形狀。綜合而論，這項研究建議一種5毫微米似肌動蛋白細絲，在高等植物粒線體中扮演著和粒線體繁殖和粒線體形態相關的角色。

關鍵字

肌動蛋白細絲；肌動蛋白動力學和線粒體形態；線粒體繁殖； Vigna radiata

並列摘要

This document reports that actin-like filaments, about 5 nm in width, were found in mung beanmitochondria after negative staining of mitoplast. The 5 nm filaments, composed of globular proteins, were visualized beneath the intramembranous particles by freeze-fracture electron microscope. Freeze-fracture immuno-labeling against anti-actin antibody suggested that actin-like filaments attached to the protoplasmic surface of mitochondrial inner membrane. These filaments were also found in the matrix and underneath of outer membrane. The presence of actin-like protein in mitochondria was also substantiated by immunolocalization in situ. Interestingly, some 5 nm filamentous bundles were often found between mitochondrion and its ”bud”. It is likely that these images represent an undiscovered novel plant mitochondrial budding process which may involve some 5 nm filamentous structure in separating nascent mitochondrion to its mother mitochondrion. Treatment of cultured tobacco cells with F-actin depolymerization reagent, Latrunculin B (Lat B) might affectthe shapes of mitochondria. Taken together, this study suggests that some 5 nm filaments, probably F-actin,may be localized in mitochondria and play a role in mitochondrial propagation and mitochondrial shaping.

並列關鍵字

Actin/actin-like filament ； Actin dynamics and mitochondrial morphology ； Mitochondrial propagation ； Vigna radiata

國際替代計量

Ultrastructural Studies on Actin-like Filament in Mung Bean Mitochondria and Its Potential Functional Significance

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