共查询到20条相似文献,搜索用时 15 毫秒
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Ligand-gated ion channels, a major class of cell-surface proteins, have a pseudosymmetric structure with five highly homologous subunits arranged around a central ion pore. The correct assembly of each channel, whose subunit composition varies with cell type and stage of development, requires specific recognition between the subunits. Assembly of the pentameric form of the acetylcholine receptor from adult muscle (AChR; alpha 2 beta epsilon delta) proceeds by a stepwise pathway starting with the formation of the heterodimers, alpha epsilon and alpha delta. The heterodimers than associate with the beta subunit and with each other to form the complete receptor. We have now determined which parts of the subunits mediate the interactions during assembly of the adult form of the receptor from mouse muscle by using a chimaeric subunit in which the N-terminal and C-terminal extracellular domains are derived from the epsilon subunit with the remainder from the beta subunit. The epsilon and beta subunits were chosen because the epsilon subunit forms a heterodimer with the alpha subunit in the pathway for assembly of the receptor, whereas the beta subunit does not. The epsilon beta chimera can substitute for the epsilon but not the beta subunit in the oligomeric receptor, indicating that the alpha subunit specifically recognizes an extracellular domain of the epsilon subunit. 相似文献
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A Sainsard 《Nature》1975,257(5524):312-314
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以人肾脏组织cDNA为模板,用PCR技术克隆了编码人Megalin基因四个结构域的cDNA,并对其进行了测序.结果表明,编码人Megalin基因四个结构域的cDNA长度分别为863bp、1,008 bp、1,247 bp及1,359 bp.编码第一结构域的cDNA序列与GenBank报道的序列有99.9%的同源性,其中两个位点有差异(第457位和605位分别为C和G,而非G和A);其余三个结构域对应的基因序列与GenBank报道的序列完全相同. 相似文献
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Efficient gene transfer by cytoplasm co-injection will offer a powerful means for transgenic animals. Using co-injection in cytoplasm, two independent gene constructs, including bovine α-s1-casein-hG-CSF and a mammal expression vector expressing a nuclear localization signal (mNLS), were introduced into fertilized mouse eggs. The target gene construct was docked into host nucleus probably by the nuclear localization signal. Transgene mice have been obtained at 58% (29/50) of integration ratio. Expression level of the positive transgene mice was detected by Western blotting. Maximal expression of human G-CSF was estimated about 540 mg/L of milk. The expression ratio was up to 75% (9/12). The results here have important practical implications for the generation of mammary gland bioreactors and other transgene studies. Co-injection of a target gene with an expression vector of a mammal nuclear localization signal by cytoplasm appears to be a useful, efficient and easy strategy for generating transgenic animals, which may be able to substitute the routine method of pronucleus-injection of fertilized eggs. 相似文献
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Human lipocortin similar to ras gene products 总被引:1,自引:0,他引:1
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ZHANG Yue SHAN Xiangnian Liu Ningsheng LU Xiaoxuan NIE Wenhui YANG Fengtang Wang Jinhuan Chen Yuze 《自然科学进展(英文版)》2001,11(9)
The chromosomes 1, Y1, Y2 of Muntjac munticus vaginalis were isolated by fluorescence activated chromosome sorting and amplified by degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR). A primer pair within human Sry HMG box was designed and the Sry gene of the male M. m vaginalis was amplified. The product was cloned and sequenced. The result proved that Sry is located on chromosome Y2, which is the sex-determining chromosome in the male M. m vaginalis. 相似文献
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B A McClure V Haring P R Ebert M A Anderson R J Simpson F Sakiyama A E Clarke 《Nature》1989,342(6252):955-957
Self-incompatibility in flowering plants is often controlled by a single nuclear gene (the S-gene) having several alleles. This gene prevents fertilization by self-pollen or by pollen bearing either of the two S-alleles expressed in the style. Sequence analysis shows that three alleles of the S gene of Nicotiana alata encode style glycoproteins with regions of defined homology. Two of the homologous regions also show precise homology with ribonucleases T2 (ref. 4) and Rh (ref. 5). We report here that glycoproteins corresponding to the S1, S2, S3, S6 and S7 alleles isolated from style extracts of N. alata are ribonucleases. These style S-gene-encoded glycoproteins account for most of the ribonuclease activity recovered from style extracts. The ribonuclease specific activity of style extracts of the self-incompatible species N. alata is 100-1,000-fold higher than that of the related self-compatible species N. tabacum. These observations implicate ribonuclease activity in the mechanism of gametophytic self-incompatibility. 相似文献
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W F Bodmer C J Bailey J Bodmer H J Bussey A Ellis P Gorman F C Lucibello V A Murday S H Rider P Scambler 《Nature》1987,328(6131):614-616
Colorectal cancer is the second most common cancer in the United Kingdom and other developed countries in the West. Although it is usually not familial, there is a rare dominantly inherited susceptibility to colon cancer, familial adenomatous polyposis (FAP; also often previously called familial polyposis coli). During adolescence affected individuals develop from a few hundred to over a thousand adenomatous polyps in their large bowel. These are sufficiently likely to give rise to adenocarcinomas to make prophylactic removal of the colon usual in diagnosed FAP individuals. Adenomas may occur elsewhere in the gastrointestinal tract and the condition is often associated with other extracolonic lesions, such as epidermoid cysts, jaw osteomata and fibrous desmoid tumours. Adenomata have been suggested to be precancerous states for most colorectal tumours. Knudson has suggested that the mutation for a dominantly inherited cancer susceptibility may be the first step in a recessive change in the tumour cells, and that the same gene may be involved in both familial and non-familial cases of a given tumour. Following up a case report of an interstitial deletion of chromosome 5 in a mentally retarded individual with multiple developmental abnormalities and FAP, we have now shown that the FAP gene is on chromosome 5, most probably near bands 5q21-q22. 相似文献
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Drosophila muscle myosin heavy chain is encoded by a single-copy gene which is transcribed during both larval and adult development. This myosin gene maps to a chromosomal locus distant from any of the actin genes, but is within a cluster of flight muscle mutations. 相似文献
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通过献资料法阐述了运动对骨骼肌基因表达的影响,以便深入理解骨骼肌的工作原理,为客观指导运动训练提供依据. 相似文献
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Localization of creatine kinase in microsomes and mitochondria of human heart and skeletal muscle and cerebral cortex 总被引:2,自引:0,他引:2
T O Kleine 《Nature》1965,207(5004):1393-1394
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Metzger T Gache V Xu M Cadot B Folker ES Richardson BE Gomes ER Baylies MK 《Nature》2012,484(7392):120-124
The basic unit of skeletal muscle in all metazoans is the multinucleate myofibre, within which individual nuclei are regularly positioned. The molecular machinery responsible for myonuclear positioning is not known. Improperly positioned nuclei are a hallmark of numerous diseases of muscle, including centronuclear myopathies, but it is unclear whether correct nuclear positioning is necessary for muscle function. Here we identify the microtubule-associated protein ensconsin (Ens)/microtubule-associated protein 7 (MAP7) and kinesin heavy chain (Khc)/Kif5b as essential, evolutionarily conserved regulators of myonuclear positioning in Drosophila and cultured mammalian myotubes. We find that these proteins interact physically and that expression of the Kif5b motor domain fused to the MAP7 microtubule-binding domain rescues nuclear positioning defects in MAP7-depleted cells. This suggests that MAP7 links Kif5b to the microtubule cytoskeleton to promote nuclear positioning. Finally, we show that myonuclear positioning is physiologically important. Drosophila ens mutant larvae have decreased locomotion and incorrect myonuclear positioning, and these phenotypes are rescued by muscle-specific expression of Ens. We conclude that improper nuclear positioning contributes to muscle dysfunction in a cell-autonomous fashion. 相似文献