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排序方式: 共有244条查询结果,搜索用时 15 毫秒
71.
Cross partition and isoelectric points of proteins 总被引:3,自引:0,他引:3
72.
Gene regulation: reviving the message 总被引:2,自引:0,他引:2
73.
Most mitochondrial proteins are synthesized on cytoplasmic ribosomes and imported into mitochondria. The imported proteins are directed to one of four submitochondrial compartments--the outer mitochondrial membrane, the inner mitochondrial membrane, the intramembraneous space, or the matrix--where the protein then functions. Here we show that the steroidogenic acute regulatory protein (StAR), a mitochondrial protein required for stress responses, reproduction, and sexual differentiation of male fetuses, exerts its activity transiently at the outer mitochondrial membrane rather than at its final resting place in the matrix. We also show that its residence time at this outer membrane and its activity are regulated by its speed of mitochondrial import. This may be the first example of a mitochondrial protein exerting its biological activity in a compartment other than that to which it is finally targeted. This system enables steroidogenic cells to initiate and terminate massive levels of steroidogenesis within a few minutes, permitting the rapid regulation of serum steroid hormone concentrations. 相似文献
74.
Timm Schubert Corinna Gleiser Peter Heiduschka Christoph Franz Kerstin Nagel-Wolfrum Ayse Sahaboglu Nicole Weisschuh Gordon Eske Karin Rohbock Norman Rieger François Paquet-Durand Bernd Wissinger Uwe Wolfrum Bernhard Hirt Wibke Singer Lukas Rüttiger Ulrike Zimmermann Marlies Knipper 《Cellular and molecular life sciences : CMLS》2015,72(20):3953-3969
75.
Hatching chronology of Blue Grouse ( Dendragapus obscurus ) in northeastern Oregon was determined from 431 immatures examined from 1981 to 1985. Young hatched from 1 May through 8 July; median hatching dates for the five years ranged from 27 May to 5 June. Peak hatching in Oregon occurred from one to four weeks earlier than in most portions of the range of Blue Grouse but were similar to north central Washington and Idaho. Variations in hatching dates possibly were related to rainfall. 相似文献
76.
77.
Chapman HN Fromme P Barty A White TA Kirian RA Aquila A Hunter MS Schulz J DePonte DP Weierstall U Doak RB Maia FR Martin AV Schlichting I Lomb L Coppola N Shoeman RL Epp SW Hartmann R Rolles D Rudenko A Foucar L Kimmel N Weidenspointner G Holl P Liang M Barthelmess M Caleman C Boutet S Bogan MJ Krzywinski J Bostedt C Bajt S Gumprecht L Rudek B Erk B Schmidt C Hömke A Reich C Pietschner D Strüder L Hauser G Gorke H Ullrich J Herrmann S Schaller G Schopper F Soltau H Kühnel KU Messerschmidt M 《Nature》2011,470(7332):73-77
X-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded. It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells. Here we present a method for structure determination where single-crystal X-ray diffraction 'snapshots' are collected from a fully hydrated stream of nanocrystals using femtosecond pulses from a hard-X-ray free-electron laser, the Linac Coherent Light Source. We prove this concept with nanocrystals of photosystem I, one of the largest membrane protein complexes. More than 3,000,000 diffraction patterns were collected in this study, and a three-dimensional data set was assembled from individual photosystem I nanocrystals (~200?nm to 2?μm in size). We mitigate the problem of radiation damage in crystallography by using pulses briefer than the timescale of most damage processes. This offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage. 相似文献
78.
Walter Dällenbach 《Cellular and molecular life sciences : CMLS》1946,2(12):490-492
Summary New proposals concerning machines for the acceleration of electrically charged particles are briefly described with two examples (heavy particles, electrons). 相似文献
79.
Translocation of lipid-linked oligosaccharides across the ER membrane requires Rft1 protein. 总被引:6,自引:0,他引:6
Jonne Helenius Davis T W Ng Cristina L Marolda Peter Walter Miguel A Valvano Markus Aebi 《Nature》2002,415(6870):447-450
N-linked glycosylation of proteins in eukaryotic cells follows a highly conserved pathway. The tetradecasaccharide substrate (Glc3Man9GlcNAc2) is first assembled at the membrane of the endoplasmic reticulum (ER) as a dolichylpyrophosphate (Dol-PP)-linked intermediate, and then transferred to nascent polypeptide chains in the lumen of the ER. The assembly of the oligosaccharide starts on the cytoplasmic side of the ER membrane with the synthesis of a Man5GlcNAc2-PP-Dol intermediate. This lipid-linked intermediate is then translocated across the membrane so that the oligosaccharides face the lumen of the ER, where the biosynthesis of Glc3Man9GlcNAc2-PP-Dol continues to completion. The fully assembled oligosaccharide is transferred to selected asparagine residues of target proteins. The transmembrane movement of lipid-linked Man5GlcNAc2 oligosaccharide is of fundamental importance in this biosynthetic pathway, and similar processes involving phospholipids and glycolipids are essential in all types of cells. The process is predicted to be catalysed by proteins, termed flippases, which to date have remained elusive. Here we provide evidence that yeast RFT1 encodes an evolutionarily conserved protein required for the translocation of Man5GlcNAc2-PP-Dol from the cytoplasmic to the lumenal leaflet of the ER membrane. 相似文献
80.
都市化的发展 ,使现代的农民已经不仅仅依靠传统的农业生产来生活 ,农民的策略再次强调了资本的积累。人类学家的实地调查报告表明了农村和城市的界线正在模糊化 ,许多生活在农村的农民积极从事工业、商业等活动。他们正大批地从土地上离去。 相似文献