Spectrin domains,characterized by a distinctive triple helix structure,are crucial in physiological processes,particularly in maintaining membrane shape and crosslinking cytoskeletons.Previous research on the 16th dom...Spectrin domains,characterized by a distinctive triple helix structure,are crucial in physiological processes,particularly in maintaining membrane shape and crosslinking cytoskeletons.Previous research on the 16th domain of a-spectrin repeats(R16)has yielded conflicting results:bulk experiments showed an unfolding rate approximately two orders of magnitude faster than the zero-force result extrapolated from single-molecule force spectroscopy experiments using atomic force microscopy(AFM).To address this discrepancy,we investigated the folding and unfolding rates of R16 across a broader range of forces using magnetic tweezers(MT).Our findings reveal that AFM results at higher forces cannot be directly extrapolated to the low-force regime due to a nonlinear relationship between force and the logarithm of the unfolding rate.We demonstrated that two-dimensional model,structural-elastic model,and two-pathway model can all effectively explain the experimental data when they capture the core physics of the short unfolding distance at low forces.Our study provides a more comprehensive understanding of the unfolding dynamics of the spectrin domain,resolves previous contradictory experimental results,and highlights the common basis of different theoretical models.展开更多
Spectrin-like protein has been found in a variety of plant cells. In this study, electron microscopic observation of immuno-gold labelled preparations from the leaf petiole of cucumber ( Cucumis sativus L.) shows that...Spectrin-like protein has been found in a variety of plant cells. In this study, electron microscopic observation of immuno-gold labelled preparations from the leaf petiole of cucumber ( Cucumis sativus L.) shows that it also exists in the sieve element-companion cell (SE-CC) complex, being widely distributed in P-protein filaments and sieve element reticulum (SER), in the cytoplasm and mitochondrial membrane of companion cell (CC) and in the branched plasmodesmata between sieve element (SE) and CC as well. The results suggest that this protein could be synthesized in CC and transferred to SE through plasmodesmata. Western blotting showed that spectrin-like protein existed in the protein of phloem exudate of cucumber, and its molecular weight was about 260 kD.展开更多
The interactions between human erythrocyte spectrin(SP) and Pt(II) complexes with different composition and configuration were studied by fluorescence and circular dichroism spectra. The results showed that there are ...The interactions between human erythrocyte spectrin(SP) and Pt(II) complexes with different composition and configuration were studied by fluorescence and circular dichroism spectra. The results showed that there are 4.7×10 2 binding sites of cisplatin(CDDP) in a spectrin tetramer(SPT). Among them, about 70 sites with apparent binding constant K 1】3.47×10 6 were of highest affinity, 1.8×10 2 sites with K 2 = 3.47×10 6 were of high affinity, and other 2.2×10 2 sites with K 3 = 8.77×10 5 were of low affinity. The conformation change of spectrin, depending on the concentration of Pt(II) complex and molar ratio(R) of Pt(II) complex to spectrin, was induced by the binding of Pt(II) complexes. It indicated that the interaction of both CDDP and cis diaquodiamine platinum(DADP) with SP followed a two step first order kinetic process in the first stage (1 h), and the kinetic constants were determined. In the second stage, the induced conformation change, polymerization and depolymerization of SP were probably involved. It was noticed that in the reaction of SP and Pt(II) complexes with 1,2 cyclohexanediammine isomers as chiral carrier ligand, stereo matching played a more important role than the affinity of Pt(II) to thiol groups of SP.展开更多
β spectrin is a major component of the membrane skeleton, a structure found at the plasma membrane of most animal cells. In C. elegans, the genome encodes only one
Immuno-western blots, immunofluorescence and immuno-gold labeling methods were used to study the existence and distribution of a homologue of the membrane skeleton spectrin in the pollen and pollen tube of Lilium davi...Immuno-western blots, immunofluorescence and immuno-gold labeling methods were used to study the existence and distribution of a homologue of the membrane skeleton spectrin in the pollen and pollen tube of Lilium davidii Duch. A spectrin homologue was found to exist in the pollen and pollen tube, distributed on membranes of secretory vesicles near Golgi apparatus.展开更多
Spectrin is a large,cytoskeletal,and heterodimeric protein composed of modular structure of and subunits,it typically contains 106 contiguous amino acid sequence motifs called"spectrin repeats".Spectrin is c...Spectrin is a large,cytoskeletal,and heterodimeric protein composed of modular structure of and subunits,it typically contains 106 contiguous amino acid sequence motifs called"spectrin repeats".Spectrin is crucial for maintaining the stability and structure of the cell membrane and the shape of a cell.Moreover,it contributes to diverse cell functions such as cell adhesion,cell spreading,and the cell cycle.Mutations of spectrin lead to various human diseases such as hereditary hemolytic anemia,type 5 spinocerebellar ataxia,cancer,as well as others.This review focuses on recent advances in determining the structure and function of spectrin as well as its role in disease.展开更多
It was well established recently that a membrane skeleton was present on the plasma membrane of erythrocytes and nonerythrocytes of animals. The membrane skeleton plays an important role in the maintenance of cell sha...It was well established recently that a membrane skeleton was present on the plasma membrane of erythrocytes and nonerythrocytes of animals. The membrane skeleton plays an important role in the maintenance of cell shape, regulation of cell motility and stabilizing the lipid bilayer. In the previous paper we compared the membrane proteins of the plasma membrane of leaf cells of Vicia faba with the membrane skeleton pro-展开更多
Spectrin molecules extracted from human blood ceil membrane have been examined by atomic force microscopy (AFM) without using shadowing or staining procedures. A drop of the solution containing spectrin molecules was ...Spectrin molecules extracted from human blood ceil membrane have been examined by atomic force microscopy (AFM) without using shadowing or staining procedures. A drop of the solution containing spectrin molecules was deposited on the freshly deaved mica substrate. After about 1 min, the residual solution was removed with a piece of filter paper. Afterwards the sample was imaged with a home-made atomic force microscope (AFM) in air in a constant force mode. The obtained AFM images revealed that the spectrin molecules prepared from the above procedures exhibit several kinds of structures as follows: (i) the compact rod-like spectrin heterodimers with a length of around 100 nm; (ii) bent or curved linear tetramers with a length of around 200 nm; (iii) somewhat curved spectrin hexamers, octomers or decamers with lengths of about 300, 400, or 500 nm; and (iv) high oligomers with a length above 1 000 nm.展开更多
The elongation of pollen tube is an important process of sex- ual reproduction in higher plant. Cytoskeleton plays a major regulatory role in the elongation of pollen tubes. But whether membrane skeleton is involved i...The elongation of pollen tube is an important process of sex- ual reproduction in higher plant. Cytoskeleton plays a major regulatory role in the elongation of pollen tubes. But whether membrane skeleton is involved in the pollen tube elongation is not clear. In this study, imuno- chemical detection of spectrin-like protein has been carried out in pollen tubes. By use of 2-dimensional electrophoresis(2DE) and western blotting, two spectrin-like proteins are found, one is 150 kD, and the other is 105 kD, with pI being 4.54 and 4.39, respectively. 150 kD spec- trin-like protein is located in plasma membrane of pollen tube and 105 kD spectrin-like protein is located in cytoplasm, probably functioning as a subunit to form a dimmer (210 kD) in vivo. The elongation of pollen tubes is inhibited after spectrin antibody was injected into a growing pollen tube. These results suggest that spectrin-like proteins exist in pollen tube and play an important regulating role in the elongation proc- ess of pollen tubes from lily.展开更多
基金supported by the National Natural Science Foun-dation of China(Grant Nos.12174322,12474200,32271367,and 12204389)111 Project(B16029)Research Grant from Wenzhou Institute.
文摘Spectrin domains,characterized by a distinctive triple helix structure,are crucial in physiological processes,particularly in maintaining membrane shape and crosslinking cytoskeletons.Previous research on the 16th domain of a-spectrin repeats(R16)has yielded conflicting results:bulk experiments showed an unfolding rate approximately two orders of magnitude faster than the zero-force result extrapolated from single-molecule force spectroscopy experiments using atomic force microscopy(AFM).To address this discrepancy,we investigated the folding and unfolding rates of R16 across a broader range of forces using magnetic tweezers(MT).Our findings reveal that AFM results at higher forces cannot be directly extrapolated to the low-force regime due to a nonlinear relationship between force and the logarithm of the unfolding rate.We demonstrated that two-dimensional model,structural-elastic model,and two-pathway model can all effectively explain the experimental data when they capture the core physics of the short unfolding distance at low forces.Our study provides a more comprehensive understanding of the unfolding dynamics of the spectrin domain,resolves previous contradictory experimental results,and highlights the common basis of different theoretical models.
文摘Spectrin-like protein has been found in a variety of plant cells. In this study, electron microscopic observation of immuno-gold labelled preparations from the leaf petiole of cucumber ( Cucumis sativus L.) shows that it also exists in the sieve element-companion cell (SE-CC) complex, being widely distributed in P-protein filaments and sieve element reticulum (SER), in the cytoplasm and mitochondrial membrane of companion cell (CC) and in the branched plasmodesmata between sieve element (SE) and CC as well. The results suggest that this protein could be synthesized in CC and transferred to SE through plasmodesmata. Western blotting showed that spectrin-like protein existed in the protein of phloem exudate of cucumber, and its molecular weight was about 260 kD.
文摘The interactions between human erythrocyte spectrin(SP) and Pt(II) complexes with different composition and configuration were studied by fluorescence and circular dichroism spectra. The results showed that there are 4.7×10 2 binding sites of cisplatin(CDDP) in a spectrin tetramer(SPT). Among them, about 70 sites with apparent binding constant K 1】3.47×10 6 were of highest affinity, 1.8×10 2 sites with K 2 = 3.47×10 6 were of high affinity, and other 2.2×10 2 sites with K 3 = 8.77×10 5 were of low affinity. The conformation change of spectrin, depending on the concentration of Pt(II) complex and molar ratio(R) of Pt(II) complex to spectrin, was induced by the binding of Pt(II) complexes. It indicated that the interaction of both CDDP and cis diaquodiamine platinum(DADP) with SP followed a two step first order kinetic process in the first stage (1 h), and the kinetic constants were determined. In the second stage, the induced conformation change, polymerization and depolymerization of SP were probably involved. It was noticed that in the reaction of SP and Pt(II) complexes with 1,2 cyclohexanediammine isomers as chiral carrier ligand, stereo matching played a more important role than the affinity of Pt(II) to thiol groups of SP.
文摘β spectrin is a major component of the membrane skeleton, a structure found at the plasma membrane of most animal cells. In C. elegans, the genome encodes only one
文摘Immuno-western blots, immunofluorescence and immuno-gold labeling methods were used to study the existence and distribution of a homologue of the membrane skeleton spectrin in the pollen and pollen tube of Lilium davidii Duch. A spectrin homologue was found to exist in the pollen and pollen tube, distributed on membranes of secretory vesicles near Golgi apparatus.
基金supported by the National Natural Science Foundation of China(31000323,31070672,81250044)the Natural Science Foundation of Jiangsu Province(BK20131272)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(20100091120023)the Fundamental Research Funds for the Central Universities(1095020823)
文摘Spectrin is a large,cytoskeletal,and heterodimeric protein composed of modular structure of and subunits,it typically contains 106 contiguous amino acid sequence motifs called"spectrin repeats".Spectrin is crucial for maintaining the stability and structure of the cell membrane and the shape of a cell.Moreover,it contributes to diverse cell functions such as cell adhesion,cell spreading,and the cell cycle.Mutations of spectrin lead to various human diseases such as hereditary hemolytic anemia,type 5 spinocerebellar ataxia,cancer,as well as others.This review focuses on recent advances in determining the structure and function of spectrin as well as its role in disease.
文摘It was well established recently that a membrane skeleton was present on the plasma membrane of erythrocytes and nonerythrocytes of animals. The membrane skeleton plays an important role in the maintenance of cell shape, regulation of cell motility and stabilizing the lipid bilayer. In the previous paper we compared the membrane proteins of the plasma membrane of leaf cells of Vicia faba with the membrane skeleton pro-
基金Project supported by the National Natural Science Foundation of China
文摘Spectrin molecules extracted from human blood ceil membrane have been examined by atomic force microscopy (AFM) without using shadowing or staining procedures. A drop of the solution containing spectrin molecules was deposited on the freshly deaved mica substrate. After about 1 min, the residual solution was removed with a piece of filter paper. Afterwards the sample was imaged with a home-made atomic force microscope (AFM) in air in a constant force mode. The obtained AFM images revealed that the spectrin molecules prepared from the above procedures exhibit several kinds of structures as follows: (i) the compact rod-like spectrin heterodimers with a length of around 100 nm; (ii) bent or curved linear tetramers with a length of around 200 nm; (iii) somewhat curved spectrin hexamers, octomers or decamers with lengths of about 300, 400, or 500 nm; and (iv) high oligomers with a length above 1 000 nm.
文摘The elongation of pollen tube is an important process of sex- ual reproduction in higher plant. Cytoskeleton plays a major regulatory role in the elongation of pollen tubes. But whether membrane skeleton is involved in the pollen tube elongation is not clear. In this study, imuno- chemical detection of spectrin-like protein has been carried out in pollen tubes. By use of 2-dimensional electrophoresis(2DE) and western blotting, two spectrin-like proteins are found, one is 150 kD, and the other is 105 kD, with pI being 4.54 and 4.39, respectively. 150 kD spec- trin-like protein is located in plasma membrane of pollen tube and 105 kD spectrin-like protein is located in cytoplasm, probably functioning as a subunit to form a dimmer (210 kD) in vivo. The elongation of pollen tubes is inhibited after spectrin antibody was injected into a growing pollen tube. These results suggest that spectrin-like proteins exist in pollen tube and play an important regulating role in the elongation proc- ess of pollen tubes from lily.
