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101.
Ningning Zhao Junwei Gao Caroline A. Enns Mitchell D. Knutson 《The Journal of biological chemistry》2010,285(42):32141-32150
ZIP14 is a transmembrane metal ion transporter that is abundantly expressed in the liver, heart, and pancreas. Previous studies of HEK 293 cells and the hepatocyte cell lines AML12 and HepG2 established that ZIP14 mediates the uptake of non-transferrin-bound iron, a form of iron that appears in the plasma during pathologic iron overload. In this study we investigated the role of ZIP14 in the cellular assimilation of iron from transferrin, the circulating plasma protein that normally delivers iron to cells by receptor-mediated endocytosis. We also determined the subcellular localization of ZIP14 in HepG2 cells. We found that overexpression of ZIP14 in HEK 293T cells increased the assimilation of iron from transferrin without increasing levels of transferrin receptor 1 or the uptake of transferrin. To allow for highly specific and sensitive detection of endogenous ZIP14 in HepG2 cells, we used a targeted knock-in approach to generate a cell line expressing a FLAG-tagged ZIP14 allele. Confocal microscopic analysis of these cells detected ZIP14 at the plasma membrane and in endosomes containing internalized transferrin. HepG2 cells in which endogenous ZIP14 was suppressed by siRNA assimilated 50% less iron from transferrin compared with controls. The uptake of transferrin, however, was unaffected. We also found that ZIP14 can mediate the transport of iron at pH 6.5, the pH at which iron dissociates from transferrin within the endosome. These results suggest that endosomal ZIP14 participates in the cellular assimilation of iron from transferrin, thus identifying a potentially new role for ZIP14 in iron metabolism. 相似文献
102.
Topors is a DNA topoisomerase I- and p53-binding protein, and mainly functions as a p53 regulator. Accumulating evidence also
supports the notion that Topors plays the role as a negative regulator of cell growth, and possibly as a tumor suppressor.
Here, we demonstrated that Topors is also involved in normal mitotic progression, since Topors depletion delays mitotic entry
and affects mitotic progression. Furthermore, Topors is degradated in response to the activation of the spindle checkpoint.
Significantly, Polo-like kinase 1 (Plk1)-associated phosphorylation of Topors at S718 is essential for nocodazole-induced
degradation of Topors. 相似文献
103.
104.
The phorbol myristate acetate (PMA) stimulated nutrophil respiratory burst has been considered to simply involve the activation of protein kinase C (PKC). However, the PLD activity was also increased by 10‐fold in human neutrophils stimulated with 100 nM PMA. Unexpectedly, U73122, an inhibitor of phospholipase C, was found to significantly inhibit PMA‐stimulated respiratory burst in human neutrophils. U73122 at the concentrations, which were sufficient to inhibit the respiratory burst completely, caused partial inhibition of the PLD activity but no inhibition on PKC translocation and activation, suggesting that PLD activity is also required in PMA‐stimulated respiratory burst. Using 1‐butanol, a PLD substrate, to block phosphatidic acid (PA) generation, the PMA‐stimulated neutrophil respiratory burst was also partially inhibited, further indicating that PLD activation, possibly its hydrolytic product PA and diacylglycerol (DAG), is involved in PMA‐stimulated respiratory burst. Since GF109203X, an inhibitor of PKC that could completely inhibit the respiratory burst in PMA‐stimulated neutrophils, also caused certain suppression of PLD activation, it may suggest that PLD activation in PMA‐stimulated neutrophils might be, to some extent, PKC dependent. To further study whether PLD contributes to the PMA stimulated respiratory burst through itself or its hydrolytic product, 1,2‐dioctanoyl‐sn‐glycerol, an analogue of DAG , was used to prime cells at low concentration, and it reversed the inhibition of PMA‐stimulated respiratory burst by U73122. The results indicate that U73122 may act as an inhibitor of PLD, and PLD activation is required in PMA‐stimulated respiratory burst. 相似文献
105.
Shu-Qun Liu Yan Tao Zhao-Hui Meng Yun-Xin Fu Ke-Qin Zhang 《Journal of molecular modeling》2011,17(2):289-300
The native serine protease proteinase K binds two calcium cations. It has been reported that Ca2+ removal decreased the enzyme’s thermal stability and to some extent the substrate affinity, but has discrepant effects on
catalytic activity of the enzyme. Molecular dynamics simulations were performed on the Ca2+-bound and Ca2+-free proteases to investigate the mechanism by which the calciums affect the structural stability, molecular motions, and
catalytic activity of proteinase K. Very similar structural properties were observed between these two forms of proteinase
K during simulations; and several long-lived hydrogen bonds and salt bridges common to both forms of proteinase K were found
to be crucial in maintaining the local conformations around these two Ca2+ sites. Although Ca2+ removal enhanced the overall flexibility of proteinase K, the flexibility in a limited number of segments surrounding the
substrate-binding pockets decreased. The largest differences in the equilibrium structures of the two simulations indicate
that, upon the removal of Ca2+, the large concerted motion originating from the Ca1 site can transmit to the substrate-binding regions but not to the catalytic
triad residues. In conjunction with the large overlap of the essential subspaces between the two simulations, these results
not only provide insight into the dynamics of the underlying molecular mechanism responsible for the unchanged enzymatic activity
as well as the decreased thermal stability and substrate affinity of proteinase K upon Ca2+ removal, but also complement the experimentally determined structural and biochemical data. 相似文献
106.
Li Zhang Shan Lei Hui Xie Qianqian Li Shuo Liu Qiang Liu Weijin Huang Xinyue Xiao Youchun Wang 《中国病毒学》2020,35(2):235-239
正Dear Editor,Marburg virus(MARV) belongs to the Filoviridae family,along with the related Ebola virus(EBOV). Although MARV is less renowned than EBOV, it causes an equally devastating disease, with clinical symptoms similar to EBOV infection and a remarkably high mortality rate. To 相似文献
107.
108.
Rebecca R. Sharitz Susan A. Wineriter Michael H. Smith Edwin H. Liu 《American journal of botany》1980,67(9):1297-1303
Biochemical phenotsypes of four taxa of Typha from the eastern United States were determined by starch gel electrophoresis. The isozyme banding patterns of T. latifolia, T. angustifolia and T. domingensis are distinct and allow unambiguous species identification when morphological characters are inadequate or unsuitable. The fourth form, T. glauca, is not an F1 hybrid, but it does appear to be intermediate between T. latifolia and T. angustifolia. The status of T. glauca and evolutionary relationships among the four forms may now be clarified by additional sampling because of the distinct and relatively invariant isozyme banding patterns which are described. 相似文献
109.
110.
Liu Xia Ruan Zhi Shao Xing-cheng Feng Hong-xuan Wu Lei Wang Wei Wang Hong-min Mu Hong-yan Zhang Ru-jun Zhao Wei-min Zhang Hai-yan Zhang Nai-xia 《Neurochemical research》2021,46(3):699-700
Neurochemical Research - In the original version of this article, unfortunately the Fig. 3C and 3F were published with incorrect version. The correct version of the Fig. 3C and 3F... 相似文献