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热休克蛋白90(HSP90)是一类ATPase依赖性蛋白,作为分子伴侣,可在辅分子伴侣协助下,通过自身构象改变,参与众多细胞的生物学事件,从而协助新合成蛋白的正确折叠、成功装配、功能稳定及异常蛋白的降解过程。HSP90功能的发挥依赖于辅分子伴侣及氨基末端结合的核苷酸。辅分子伴侣是一类可与分子伴侣(如,HSP90)结合并调节其功能的蛋白,通过参与ATPase循环从而调节HSP90分子伴侣的功能。近年来,辅分子伴侣的研究得到越来越多的关注,本文就辅分子伴侣调控HSP90功能的作用进行综述。 相似文献
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DuaJ-like蛋白由N-端保守的J区域、富含Gly和Phe区域、富含Cys区域和C-端低同源区域组成。J功能域能调节HSP70分子伴侣的ATPase活性,C-端不保守区域能调节与多肽的关系。真核细胞中存在着多种结构不同的DuaJ-like蛋白,但都含有一个J功能域。DuaJ-like蛋白通过J功能域调节HSP70功能而参与蛋白的折叠、装配和运输过程。 相似文献
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大肠杆菌分子伴侣GroE系统及其协助的Rubisco蛋白装配 总被引:1,自引:0,他引:1
分子伴侣协助蛋白质在体内正确组装,对分子伴侣结构和作用机制的研究不仅在生物大分子结构和功能研究中具有重要的理论意义,而且还具有广泛的应用价值。大肠杆菌分子伴侣GroE系统是迄今为止研究得最为透彻的分子伴侣。本文侧重总结了GroE系统的作用机制以及在该系统的帮助下光合细菌核酮糖1,5二磷酸羧化/加氧酶(Rubisco蛋白)的装配情况。 相似文献
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Ⅲ型分泌系统分子伴侣研究进展 总被引:8,自引:0,他引:8
Ⅲ型分泌系统广泛存在于革兰氏阴性致病菌中。通过Ⅲ型分泌系统 ,耶尔森氏菌属、沙门氏菌属、福氏志贺氏菌等革兰氏阴性致病菌注射毒力因子到宿主细胞中 ,被注入的细菌毒力蛋白在宿主细胞中刺激或干扰宿主细胞的代谢过程 ,支配细菌与宿主细胞的相互作用 ,从而引起诸如鼠疫、伤寒、痢疾等许多疾病。Ⅲ型分泌系统分子伴侣在帮助毒力蛋白分泌的过程中起到重要作用。尽管发现Ⅲ型分泌系统分子伴侣至今已近十年 ,但其具体的功能仍不清楚。从分类、功能、与相应底物作用的特点等方面对Ⅲ型分泌系统分子伴侣的研究进展作一简单介绍 相似文献
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膜间质蛋白酶(DegP),是一种广泛存在于真核生物和原核生物细胞中的蛋白。DegP同时具有酶活性和分子伴侣活性,并通过多聚体构成胶囊状结构执行其分子伴侣功能。DegP的酶活性依赖酶切位点与PDZ1结构域双重识别方式识别底物,这种识别模式被称为"分子量尺"。在革兰氏阴性菌中,DegP主要位于膜间质,通过分子伴侣活性与酶活性帮助保护错误折叠蛋白或降解变性蛋白。DegP也参与外膜蛋白的转运,是DegP胞内活性的研究重点。DegP也可以被分泌到胞外,帮助宿主对抗恶劣环境,并参与调节生物被膜的形成。本文将从DegP的结构与活性、胞内功能与胞外功能三大方面对DegP的研究进展进行总结,为革兰氏阴性菌周质中蛋白质质量控制与DegP体外功能的进一步研究提供参考。 相似文献
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分子伴侣参与调控动、植物的发育和进化进程 总被引:1,自引:0,他引:1
近年来, 人们对分子伴侣的功能研究取得了很大进展, 阐明了它参与细胞新合成蛋白多肽的折叠、组装、运输和蛋白质的降解过程。在这些过程中, 伴随着分子伴侣表达量的高低变化, 细胞线粒体数量也会发生相应的变化。文章综述了分子伴侣参与调控动、植物的发育和进化进程, 如: 动、植物育性调控, 抗逆境能力提高及热休克蛋白-多肽复合物的肿瘤免疫治疗探索等。 相似文献
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Heat shock proteins of 40 kDa (Hsp40s), also called J proteins, are obligate partners of Hsp70s. Via their highly conserved and functionally critical J domain, J proteins interact and modulate the activity of their Hsp70 partners. Mutations in the critical residues in the J domain often result in the null phenotype for the J protein in question. However, as more J proteins have been characterized, it is becoming increasingly clear that a significant number of J proteins do not “completely” rely on their J domains to carry out their cellular functions, as previously thought. In some cases, regions outside the highly conserved J domain have become more important making the J domain dispensable for some, if not for all functions of a J protein. This has profound effects on the evolution of such J proteins. Here we present selected examples of J proteins that perform J domain independent functions and discuss this in the context of evolution of J proteins with dispensable J domains and J-like proteins in eukaryotes. 相似文献
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Hsp70 chaperones are involved in multiple biological processes and are recruited to specific processes by designated J domain-containing cochaperones, or J proteins. To understand the evolution and functions of chloroplast Hsp70s and J proteins, we identified the Arabidopsis chloroplast J protein constituency using a combination of genomic and proteomic database searches and individual protein import assays. We show that Arabidopsis chloroplasts have at least 19 J proteins, the highest number of confirmed J proteins for any organelle. These 19 J proteins are classified into 11 clades, for which cyanobacteria and glaucophytes only have homologs for one clade, green algae have an additional three clades, and all the other 7 clades are specific to land plants. Each clade also possesses a clade-specific novel motif that is likely used to interact with different client proteins. Gene expression analyses indicate that most land plant-specific J proteins show highly variable expression in different tissues and are down regulated by low temperatures. These results show that duplication of chloroplast Hsp70 in land plants is accompanied by more than doubling of the number of its J protein cochaperones through adding new J proteins with novel motifs, not through duplications within existing families. These new J proteins likely recruit chloroplast Hsp70 to perform tissue specific functions related to biosynthesis rather than to stress resistance. 相似文献
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DnaJ is a molecular chaperone and the prototypical member of the J-protein family. J proteins are defined by the presence of a J domain that can regulate the activity of 70-kDa heat-shock proteins. Sequence analysis on the genome of Saccharomyces cerevisiae has revealed 22 proteins that establish four distinguishing structural features of the J domain: predicted helicity in segments I-IV, precisely placed interhelical contact residues, a lysine-rich surface on helix II and placement of the diagnostic sequence HPD between the predicted helices II and III. We suggest that this definition of the J-protein family could be used for other genome-wide studies. In addition, three J-like proteins were identified in yeast that contain regions closely resembling a J domain, but in which the HPD motif is non-conservatively replaced. We suggest that J-like proteins might function to regulate the activity of bona fide J proteins during protein translocation, assembly and disassembly. 相似文献
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Characterization and primary structure of the poly(C)-binding heterogeneous nuclear ribonucleoprotein complex K protein. 总被引:42,自引:13,他引:29
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At least 20 major proteins make up the ribonucleoprotein (RNP) complexes of heterogeneous nuclear RNA (hnRNA) in mammalian cells. Many of these proteins have distinct RNA-binding specificities. The abundant, acidic heterogeneous nuclear RNP (hnRNP) K and J proteins (66 and 64 kDa, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) are unique among the hnRNP proteins in their binding preference: they bind tenaciously to poly(C), and they are the major oligo(C)- and poly(C)-binding proteins in human HeLa cells. We purified K and J from HeLa cells by affinity chromatography and produced monoclonal antibodies to them. K and J are immunologically related and conserved among various vertebrates. Immunofluorescence microscopy with antibodies shows that K and J are located in the nucleoplasm. cDNA clones for K were isolated, and their sequences were determined. The predicted amino acid sequence of K does not contain an RNP consensus sequence found in many characterized hnRNP proteins and shows no extensive homology to sequences of any known proteins. The K protein contains two internal repeats not found in other known proteins, as well as GlyArgGlyGly and GlyArgGlyGlyPhe sequences, which occur frequently in many RNA-binding proteins. Overall, K represents a novel type of hnRNA-binding protein. It is likely that K and J play a role in the nuclear metabolism of hnRNAs, particularly for pre-mRNAs that contain cytidine-rich sequences. 相似文献
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Analysis of the levels of conservation of the J domain among the various types of DnaJ-like proteins
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DnaJ-like proteins are defined by the presence of an approximately 73 amino acid region termed the J domain. This region bears similarity to the initial 73 amino acids of the Escherichia coli protein DnaJ. Although the structures of the J domains of E coli DnaJ and human heat shock protein 40 have been solved using nuclear magnetic resonance, no detailed analysis of the amino acid conservation among the J domains of the various DnaJ-like proteins has yet been attempted. A multiple alignment of 223 J domain sequences was performed, and the levels of amino acid conservation at each position were established. It was found that the levels of sequence conservation were particularly high in 'true' DnaJ homologues (ie, those that share full domain conservation with DnaJ) and decreased substantially in those J domains in DnaJ-like proteins that contained no additional similarity to DnaJ outside their J domain. Residues were also identified that could be important for stabilizing the J domain and for mediating the interaction with heat shock protein 70. 相似文献
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Up to seven early poxvirus-specific proteins have been isolated from vaccinia-WR-infected and cowpox-virus-infected chick embryo fibroblasts by affinity chromatography on native DNA-cellulose columns. The proteins have been characterized by one-dimensional sodium dodecyl sulfate/polyacrylamide gel electrophoresis and by nonequilibrium pH-gradient electrophoresis. The molecular weights of the viral proteins were determined by comparison with proteins of known molecular weight and are comparable to several of the vaccinia-WR-specific DNA-binding proteins isolated previously from infected L-929 cells by Solosky J. M., Esteban M. and Holowczak J.A. [J. Virol. 25, 263-273 (1978)]. The viral proteins binding reversibly to native DNA have been classified as immediate early viral gene products. Synthesis of cowpox-virus-induced early DNA-binding proteins is inhibited in chick cells pretreated with homologous interferon at a concentration of 500--1000 units/ml. 相似文献
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Characterization of a monoclonal antibody that induces the acrosome reaction of sea urchin sperm 总被引:6,自引:3,他引:3
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J S Trimmer Y Ebina R W Schackmann C G Meinhof V D Vacquier 《The Journal of cell biology》1987,105(3):1121-1128
A monoclonal antibody, J18/29, induces the acrosome reaction (AR) in spermatozoa of the sea urchin Strongylocentrotus purpuratus. J18/29 induces increases in both intracellular Ca2+ and intracellular pH similar to those occurring upon induction of the AR by the natural inducer, the fucose sulfate-rich glycoconjugate of egg jelly. Lowering the Ca2+ concentration or the pH of the seawater inhibits the J18/29-induced AR, as does treatment with Co2+, an inhibitor of Ca2+ channels. The J18/29-induced AR is also inhibited by verapamil, tetraethylammonium chloride, and elevated K+. All these treatments cause similar inhibition of the egg jelly-induced AR. J18/29 reacts with a group of membrane proteins ranging in molecular mass from 340 to 25 kD, as shown by immunoprecipitation of lysates of 125I-labeled sperm and Western blots. The most prominent reacting proteins are of molecular masses of 320, 240, 170, and 58 kD. The basis of the multiple reactivity appears to reside in the polypeptide chains of these proteins, as J18/29 binding is sensitive to protease digestion but resistant to periodate oxidation. There are approximately 570,000 sites per cell for J18/29 binding. J18/29 is the only reagent of known binding specificity that induces the AR; it identifies a subset of sperm membrane proteins whose individual characterization may lead to the isolation of the receptors involved in the triggering of the AR at fertilization. 相似文献
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Correia C Monzani E Moura I Lampreia J Moura JJ 《Biochemical and biophysical research communications》1999,256(2):367-371
Tetraheme cytochrome c3 (13 kDa) and flavodoxin (16 kDa), are small electron transfer proteins that have been used to mimic, in vitro, part of the electron-transfer chain that operates between substract electron donors and respiratory electron acceptors partners in Desulfovibrio species (Palma, N., Moura, I., LeGall, J., Van Beeumen, J., Wampler, J., Moura, J. J. G. (1994) Biochemistry 33, 6394-6407). The electron transfer between these two proteins is believed to occur through the formation of a specific complex where electrostatic interaction is the main driving force (Stewart, D., LeGall, J., Moura, I., Moura, J.J.G., Peck, H.D., Xavier, A.V., Weiner, P.K. and Wampler, J.E. (1988) Biochemistry 27, 2444-2450, Stewart, D., LeGall, J., Moura, I., Moura, J.J.G., Peck, H.D., Xavier, A.V., Weiner, P., Wampler, J. (1989) Eur. J. Biochem. 185, 695-700). In order to obtain structural information of the pre-complex, a covalent complex between the two proteins was prepared. A water-soluble carbodiimide [EDC (1-ethyl-3(3 dimethylaminopropyl) carbodiimide hydrochloride] was used for the cross linking reaction. The reaction was optimized varying a wide number of experimental parameters such as ionic strength, protein and cross linker concentration, and utilization of different cross linkers and reaction time between the crosslinker and proteins. 相似文献
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Hennessy F Nicoll WS Zimmermann R Cheetham ME Blatch GL 《Protein science : a publication of the Protein Society》2005,14(7):1697-1709
Heat shock protein 40s (Hsp40s) and heat shock protein 70s (Hsp70s) form chaperone partnerships that are key components of cellular chaperone networks involved in facilitating the correct folding of a broad range of client proteins. While the Hsp40 family of proteins is highly diverse with multiple forms occurring in any particular cell or compartment, all its members are characterized by a J domain that directs their interaction with a partner Hsp70. Specific Hsp40-Hsp70 chaperone partnerships have been identified that are dedicated to the correct folding of distinct subsets of client proteins. The elucidation of the mechanism by which these specific Hsp40-Hsp70 partnerships are formed will greatly enhance our understanding of the way in which chaperone pathways are integrated into finely regulated protein folding networks. From in silico analyses, domain swapping and rational protein engineering experiments, evidence has accumulated that indicates that J domains contain key specificity determinants. This review will critically discuss the current understanding of the structural features of J domains that determine the specificity of interaction between Hsp40 proteins and their partner Hsp70s. We also propose a model in which the J domain is able to integrate specificity and chaperone activity. 相似文献
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Post-translational modification of a monocyte-specific chemoattractant synthesized by glioma, osteosarcoma, and vascular smooth muscle cells 总被引:6,自引:0,他引:6
Y Jiang A J Valente M J Williamson L Zhang D T Graves 《The Journal of biological chemistry》1990,265(30):18318-18321
Chemotaxis is an important step in monocyte recruitment in inflammation, wound healing, and tumor growth. We reported previously that monocyte chemotactic activity secreted by malignant cells and normal smooth muscle cells is associated with a protein or family of proteins that are related to the monocyte-specific smooth muscle cell-derived chemotactic factor (SMC-CF) (Graves, D. T., Jiang, Y. L., Williamson, M. J., and Valente, A. J. (1989) Science 245, 1490-1493). Similar monocyte chemotactic proteins (MCP-1) produced by U-105MG human glioma cells have also been identified (Yoshimura, T., Robinson, E. A., Tanaka, S., Appella, E., Kuratsu, J., and Leonard, E. J. (1989) J. Exp. Med. 169, 1449-1459). We now report that the MCP-1 gene is expressed in MG-63 human osteosarcoma and vascular smooth muscle cells and that SMC-CF antiserum specifically immunoprecipitates proteins synthesized by U-105MG glioma cells. Experiments were undertaken to elucidate the processing pathway of MCP-1/SMC-CF-like proteins in each of these cell types. These experiments demonstrate that larger MCP-1/SMC-CF-like proteins are derived from a Mr = 9000 precursor. Post-translational modification involves the addition of O-linked carbohydrates and sialic acid residues. Differences in carbohydrate processing account for the heterogeneity in MCP-1/SMC-CF-like proteins produced by different cell types. Secretion of these proteins occurs rapidly following processing events in the endoplasmic reticulum-Golgi compartment. 相似文献