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81.
This review summarizes our present knowledge about the composition and function of the plant nuclear envelope. Compared with animals or yeast, our molecular understanding of the nuclear envelope in higher plants is in its infancy. However, fundamental differences in the structure and function of the plant and animal nuclear envelope have already been found. Here, we compare and contrast these differences with respect to nuclear pore complexes, targeting of Ran signaling to the nuclear envelope, inner nuclear envelope proteins, and the role and fate of the nuclear envelope during mitosis. Further investigation of the emerging fundamental differences as well as the similarities between kingdoms might illuminate why there appears to be more than one blueprint for building a nucleus.Abbreviations
GFP
Green fluorescent protein
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INE
Inner nuclear envelope
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LAP
Lamina-associated polypeptide
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LBR
Lamin B receptor
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MTOC
Microtubule-organizing center
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NE
Nuclear envelope
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NPC
Nuclear pore complex
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ONE
Outer nuclear envelope
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RanBP
Ran-binding protein
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RanGAP
Ran GTPase-activating protein
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WPP domain
Tryptophan–proline–proline domain 相似文献
82.
Changes in plasma gonadotropin concentrations and urethral closure pressure in the bitch during the 12 months following ovariectomy 总被引:3,自引:0,他引:3
Reichler IM Pfeiffer E Piché CA Jöchle W Roos M Hubler M Arnold S 《Theriogenology》2004,62(8):1391-1402
Urinary incontinence due to acquired urethral sphincter incompetence is a common side effect of spaying, for which the underlying cause remains unknown. Spaying not only results in a significant reduction in the urethral closure pressure within 1 year but also in an increase in the plasma gonadotropin concentrations. To investigate the possible link between the post-ovariectomy changes in plasma gonadotropins and in urethral closure pressure, gonadotropin and urodynamic measurements were performed in 10 Beagle bitches before and for a period of 1 year after spaying. Plasma gonadotropin concentrations rose quickly after ovariectomy and peak levels were seen within 3-5 weeks, followed by a sharp drop until week 10. A steady increase was observed subsequently until week 42, when a plateau was reached. One year after spaying, the mean FSH concentration was 75.3 +/- 32.1 ng/ml, a 17-fold increase, and the LH was 8.3 +/- 3.8 ng/ml, an eightfold increase over the pre-spaying values. Ten months after spaying, the mean urethral closure pressure (9.7 cm H2O) was significantly reduced when compared to the mean pre-operative value of 15.4 cm H2O. However, there was no clear relationship between the gonadotropin concentrations and the urethral closure pressure. From these results it seems unlikely that chronically elevated gonadotropins are the underlying cause for reduced urethral closure pressure after spaying resulting in urinary incontinence. 相似文献
83.
84.
Ohren JF Chen H Pavlovsky A Whitehead C Zhang E Kuffa P Yan C McConnell P Spessard C Banotai C Mueller WT Delaney A Omer C Sebolt-Leopold J Dudley DT Leung IK Flamme C Warmus J Kaufman M Barrett S Tecle H Hasemann CA 《Nature structural & molecular biology》2004,11(12):1192-1197
MEK1 and MEK2 are closely related, dual-specificity tyrosine/threonine protein kinases found in the Ras/Raf/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway. Approximately 30% of all human cancers have a constitutively activated MAPK pathway, and constitutive activation of MEK1 results in cellular transformation. Here we present the X-ray structures of human MEK1 and MEK2, each determined as a ternary complex with MgATP and an inhibitor to a resolution of 2.4 A and 3.2 A, respectively. The structures reveal that MEK1 and MEK2 each have a unique inhibitor-binding pocket adjacent to the MgATP-binding site. The presence of the potent inhibitor induces several conformational changes in the unphosphorylated MEK1 and MEK2 enzymes that lock them into a closed but catalytically inactive species. Thus, the structures reported here reveal a novel, noncompetitive mechanism for protein kinase inhibition. 相似文献
85.
Until now, the predominant use cases of industrial robots have been routine handling tasks in the automotive industry. In biotechnology and tissue engineering, in contrast, only very few tasks have been automated with robots. New developments in robot platform and robot sensor technology, however, make it possible to automate plants that largely depend on human interaction with the production process, e.g., for material and cell culture fluid handling, transportation, operation of equipment, and maintenance. In this paper we present a robot system that lends itself to automating routine tasks in biotechnology but also has the potential to automate other production facilities that are similar in process structure. After motivating the design goals, we describe the system and its operation, illustrate sample runs, and give an assessment of the advantages. We conclude this paper by giving an outlook on possible further developments. 相似文献
86.
Jonkers IJ Smelt AH Hattori H Scheek LM van Gent T de Man FH van der Laarse A van Tol A 《Journal of lipid research》2003,44(8):1462-1469
Hypertriglyceridemia (HTG) is associated with insulin resistance, increased cholesteryl ester transfer (CET), and low HDL cholesterol. Phospholipid transfer protein (PLTP) may be involved in these relationships. Associations between CET, lipids, insulin resistance, CETP and PLTP activities, and PLTP mass were investigated in 18 HTG patients and 20 controls. Effects of 6 weeks of bezafibrate treatment were studied in HTG patients. HTG patients had higher serum triglycerides, insulin resistance, free fatty acid (FFA), and CET, lower levels of HDL cholesterol (-44%) and PLTP mass (-54%), and higher CETP (+20%) and PLTP activity (+48%) than controls. Bezafibrate reduced triglycerides, CET (-37%), insulin resistance (-53%), FFA (-48%), CETP activity (-12%), PLTP activity (-8%), and increased HDL cholesterol (+27%), whereas PLTP mass remained unchanged. Regression analysis showed a positive contribution of PLTP mass (P = 0.001) but not of PLTP activity to HDL cholesterol, whereas insulin resistance positively contributed to PLTP activity (P < 0.01). Bezafibrate-induced change in CET and HDL cholesterol correlated with changes in CETP activity and FFAs, but not with change in PLTP activity. Bezafibrate-induced change in PLTP activity correlated with change in FFAs (r = 0.455, P = 0.058). We propose that elevated PLTP activity in HTG is related to insulin resistance and not to increased PLTP mass. Bezafibrate-induced diminished insulin resistance is associated with a reduction of CET and PLTP activity. 相似文献
87.
Pan-Hammarström Q Dai S Zhao Y van Dijk-Härd IF Gatti RA Børresen-Dale AL Hammarström L 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(7):3707-3716
Class switch recombination (CSR) and somatic hypermutation (SHM) are mechanistically related processes that share common key factors such as activation-induced cytidine deaminase. We have previously shown a role for ATM (mutated in ataxia-telangiectasia) in CSR. In this paper we show that the frequency, distribution, and nature of base pair substitutions in the Ig variable (V) heavy chain genes in ataxia-telangiectasia patients are largely similar to those in normal donors, suggesting a normal SHM process. Characterization of the third complementarity-determining region in B cells from ataxia-telangiectasia patients also shows a normal V(D)J recombination process. SHM-like mutations could be identified in the switch (S) mu region (up to several hundred base pairs upstream of the S mu -S(alpha) breakpoints) in normal in vivo switched human B cells. In the absence of ATM, mutations can still be found in this region, but at less than half the frequency of that in normal donors. The latter mutations are mainly due to transitions (86% compared with 58% in controls) and are biased to A or T nucleotides. An ATM-dependent mechanism, different from that generating SHM in V genes, is therefore likely to be involved in introducing SHM-like mutations in the S region. ATM may thus be one of the factors that is not shared by the CSR and SHM processes. 相似文献
88.
Nayernia K Vauti F Meinhardt A Cadenas C Schweyer S Meyer BI Schwandt I Chowdhury K Engel W Arnold HH 《The Journal of biological chemistry》2003,278(48):48377-48385
Lis1 protein is the non-catalytic component of platelet-activating factor acetylhydrolase 1b (PAF-AH 1B) and associated with microtubular structures. Hemizygous mutations of the LIS1 gene cause type I lissencephaly, a brain abnormality with developmental defects of neuronal migration. Lis1 is also expressed in testis, but its function there has not been determined. We have generated a mouse mutant (LIS1GT/GT) by gene trap integration leading to selective disruption of a Lis1 splicing variant in testis. Homozygous mutant males are infertile with no other apparent phenotype. We demonstrate that Lis1 is predominantly expressed in spermatids, and spermiogenesis is blocked when Lis1 is absent. Mutant spermatids fail to form correct acrosomes and nuclei appear distorted in size and shape. The tissue architecture in mutant testis appears severely disturbed displaying collapsed seminiferous tubules, mislocated germ cells, and increased apoptosis. These results provide evidence for an essential and hitherto uncharacterized role of the Lis1 protein in spermatogenesis, particularly in the differentiation of spermatids into spermatozoa. 相似文献
89.
Winklhofer KF Henn IH Kay-Jackson PC Heller U Tatzelt J 《The Journal of biological chemistry》2003,278(47):47199-47208
Loss of parkin function is linked to autosomal recessive juvenile parkinsonism. Here we show that proteotoxic stress and short C-terminal truncations induce misfolding of parkin. As a consequence, wild-type parkin was depleted from a high molecular weight complex and inactivated by aggregation. Similarly, the pathogenic parkin mutant W453Stop, characterized by a C-terminal deletion of 13 amino acids, spontaneously adopted a misfolded conformation. Mutational analysis indicated that C-terminal truncations exceeding 3 amino acids abolished formation of detergent-soluble parkin. In the cytosol scattered aggregates of misfolded parkin contained the molecular chaperone Hsp70. Moreover, increased expression of chaperones prevented aggregation of wild-type parkin and promoted folding of the W453Stop mutant. Analyzing parkin folding in vitro indicated that parkin is aggregation-prone and that its folding is dependent on chaperones. Our study demonstrates that C-terminal truncations impede parkin folding and reveal a new mechanism for inactivation of parkin. 相似文献
90.