After selective extraction and purification, plant keratin intermediate filaments were reassembled in vitro. Scanning tunneling microscope (STM) and transmission electron microscope (TEM) micrographs showed that acidi...After selective extraction and purification, plant keratin intermediate filaments were reassembled in vitro. Scanning tunneling microscope (STM) and transmission electron microscope (TEM) micrographs showed that acidic keratins and basic keratins can assemble into dimers and further into 10 nm filaments in vitro. In higher magnification images , it can be seen that fully assembled plant keratin intermediate filaments consist of several thinner filaments of 3 nm in diameter, which indicates the formation of protofilaments in the assembly processes. One of the explicit features of plant keratin intermediate filaments is a 24-25 nm periodic structural repeat alone the axis of both the 10 nm filaments and protofilaments. The periodic repeat is one of the fundamental characteristic of all intermediate filaments, and demonstrates the half staggered arrangement of keratin molecules within the filaments.展开更多
A delicate intermediate filament-like network of mesophyll cells was observed both in maize and tobacco, using selective extraction together with whole-mount cell preparation for electron microscopy. The filament of t...A delicate intermediate filament-like network of mesophyll cells was observed both in maize and tobacco, using selective extraction together with whole-mount cell preparation for electron microscopy. The filament of the network is about 10 nm in diameter. Further test using immuno-gold labeling with anti-keratin antibodies indicated that the component of the intermediate filament-like system was keratin-like protein. Such a keratin-like intermediate filament system existing in plant cells was demonstrated for the first time. Meanwhile, 3-nm size filaments and their connection with 10-nm filaments were also shown in maize and tobacco protoplasts.展开更多
Ⅰ. INTRODUCTION Intermediate filaments with a diameter of 10 nm, known as a cytoskeleton system, are extensively present in animal cells. Whether the intermediate filaments are present in plant cells remains to be a ...Ⅰ. INTRODUCTION Intermediate filaments with a diameter of 10 nm, known as a cytoskeleton system, are extensively present in animal cells. Whether the intermediate filaments are present in plant cells remains to be a question. Some investigators attempt to seek answers from various aspects, but it is still unsolved. Powell observed 7-nm filament in carrot suspension cells after treatment with high salt and Triton X-100. Dawson and Miller showed展开更多
Two keratin-like proteins of 64 and 55 ku were purified from suspension cells of Caucus carota L, and their partial amino acid sequences were determined. The homological analysis showed that the sequence from the 64 k...Two keratin-like proteins of 64 and 55 ku were purified from suspension cells of Caucus carota L, and their partial amino acid sequences were determined. The homological analysis showed that the sequence from the 64 ku protein was highly homological to p-glucosidase, and that from the 55 ku protein had no significant homologue in GenBank. Using conservative sequence of animal IF proteins as primer, we cloned a cDNA fragment from Daucus carota L. Southern blot and Northern blot results indicated that this cDNA fragment was a single copy gene and expressed both in suspension cells and leaves. Homological analysis revealed that it had moderate homology to a variety of a-helical proteins. Our results might shed more light on molecular characterization of IF existence in higher plant.展开更多
Delicate networks of 10-nm filaments were found to exist widely in suspension cells of cultured carrot and root tip cells of pea by selective extraction combined with whole mount and diethylene glycol distearate plast...Delicate networks of 10-nm filaments were found to exist widely in suspension cells of cultured carrot and root tip cells of pea by selective extraction combined with whole mount and diethylene glycol distearate plastic embedment-free section for electron microscopy. These filament components are polypeptides of 52, 58, 62—64 and 50kD using Western blot analysis. A relatively uniform 10-nm filaments, as well as bundle of such filaments could be reconstituted in vitro. The reconstituted filaments were indistinguishable from native plant intermediate filaments in morphology and protein components. Thus the intermediate filaments are actually present in cytoplasm of higher plants. We also found no obvious specificity in tissues and species by comparison of the proteins among various types of plant cells.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 39370352)the Doctor Foundation of Ministry of Education of China.
文摘After selective extraction and purification, plant keratin intermediate filaments were reassembled in vitro. Scanning tunneling microscope (STM) and transmission electron microscope (TEM) micrographs showed that acidic keratins and basic keratins can assemble into dimers and further into 10 nm filaments in vitro. In higher magnification images , it can be seen that fully assembled plant keratin intermediate filaments consist of several thinner filaments of 3 nm in diameter, which indicates the formation of protofilaments in the assembly processes. One of the explicit features of plant keratin intermediate filaments is a 24-25 nm periodic structural repeat alone the axis of both the 10 nm filaments and protofilaments. The periodic repeat is one of the fundamental characteristic of all intermediate filaments, and demonstrates the half staggered arrangement of keratin molecules within the filaments.
文摘A delicate intermediate filament-like network of mesophyll cells was observed both in maize and tobacco, using selective extraction together with whole-mount cell preparation for electron microscopy. The filament of the network is about 10 nm in diameter. Further test using immuno-gold labeling with anti-keratin antibodies indicated that the component of the intermediate filament-like system was keratin-like protein. Such a keratin-like intermediate filament system existing in plant cells was demonstrated for the first time. Meanwhile, 3-nm size filaments and their connection with 10-nm filaments were also shown in maize and tobacco protoplasts.
基金Project supported by the National Natural Science Foundation of China
文摘Ⅰ. INTRODUCTION Intermediate filaments with a diameter of 10 nm, known as a cytoskeleton system, are extensively present in animal cells. Whether the intermediate filaments are present in plant cells remains to be a question. Some investigators attempt to seek answers from various aspects, but it is still unsolved. Powell observed 7-nm filament in carrot suspension cells after treatment with high salt and Triton X-100. Dawson and Miller showed
文摘Two keratin-like proteins of 64 and 55 ku were purified from suspension cells of Caucus carota L, and their partial amino acid sequences were determined. The homological analysis showed that the sequence from the 64 ku protein was highly homological to p-glucosidase, and that from the 55 ku protein had no significant homologue in GenBank. Using conservative sequence of animal IF proteins as primer, we cloned a cDNA fragment from Daucus carota L. Southern blot and Northern blot results indicated that this cDNA fragment was a single copy gene and expressed both in suspension cells and leaves. Homological analysis revealed that it had moderate homology to a variety of a-helical proteins. Our results might shed more light on molecular characterization of IF existence in higher plant.
基金Project supported by the National Natural Science Foundation of China.
文摘Delicate networks of 10-nm filaments were found to exist widely in suspension cells of cultured carrot and root tip cells of pea by selective extraction combined with whole mount and diethylene glycol distearate plastic embedment-free section for electron microscopy. These filament components are polypeptides of 52, 58, 62—64 and 50kD using Western blot analysis. A relatively uniform 10-nm filaments, as well as bundle of such filaments could be reconstituted in vitro. The reconstituted filaments were indistinguishable from native plant intermediate filaments in morphology and protein components. Thus the intermediate filaments are actually present in cytoplasm of higher plants. We also found no obvious specificity in tissues and species by comparison of the proteins among various types of plant cells.
