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1.
The 4.1-like proteins of the bovine lens: spectrin-binding proteins closely related in structure to red blood cell protein 4.1 总被引:3,自引:1,他引:2 下载免费PDF全文
The superficial cortical fiber cells of the bovine lens contain membrane-associated proteins of 150,000, 80,000, and 78,000 D that cross-react with antisera prepared against red blood cell (RBC) protein 4.1 (Aster, J. C., G. J. Brewer, S. M. Hanash, and H. Maisel, 1984, Biochem. J., 224:609-616). To further study their relationship to protein 4.1, these proteins were immunoprecipitated from detergent extracts of crude lens membranes with purified polyclonal and monoclonal anti-4.1 antibodies and resolved by SDS PAGE. The electrophoretic mobilities of the lens proteins of 80,000 and 78,000 D were found to be identical to bovine RBC protein 4.1a and protein 4.1b, respectively. One- and two-dimensional peptide mapping revealed that a high degree of structural homology exists among all three of the lens 4.1-like proteins and RBC protein 4.1a and protein 4.1b. Despite the large difference in apparent molecular mass, the 150,000-D lens protein showed only minor peptide map differences. A nitrocellulose filter overlay assay showed that all three of the lens 4.1-like proteins bind to RBC and lens spectrins. We conclude that the bovine lens contains proteins of 80,000 and 78,000 D that are highly similar to protein 4.1 in structure and functional capacity. Additionally, the lens also contains a 4.1 isomorph of 150 kD. Analogous to RBC protein 4.1, these proteins may function in the lens by promoting association of spectrin with actin and by playing a role in the coupling of lens cytoskeleton to plasma membrane. 相似文献
2.
Sarah Oddoux Kristien J. Zaal Victoria Tate Aster Kenea Shuktika A. Nandkeolyar Ericka Reid Wenhua Liu Evelyn Ralston 《The Journal of cell biology》2013,203(2):205-213
Skeletal muscle microtubules (MTs) form a nonclassic grid-like network, which has so far been documented in static images only. We have now observed and analyzed dynamics of GFP constructs of MT and Golgi markers in single live fibers and in the whole mouse muscle in vivo. Using confocal, intravital, and superresolution microscopy, we find that muscle MTs are dynamic, growing at the typical speed of ∼9 µm/min, and forming small bundles that build a durable network. We also show that static Golgi elements, associated with the MT-organizing center proteins γ-tubulin and pericentrin, are major sites of muscle MT nucleation, in addition to the previously identified sites (i.e., nuclear membranes). These data give us a framework for understanding how muscle MTs organize and how they contribute to the pathology of muscle diseases such as Duchenne muscular dystrophy. 相似文献
3.
Jelena Petrovic Yeqiao Zhou Maria Fasolino Naomi Goldman Gregory W. Schwartz Maxwell R. Mumbach Son C. Nguyen Kelly S. Rome Yogev Sela Zachary Zapataro Stephen C. Blacklow Michael J. Kruhlak Junwei Shi Jon C. Aster Eric F. Joyce Shawn C. Little Golnaz Vahedi Warren S. Pear Robert B. Faryabi 《Molecular cell》2019,73(6):1174-1190.e12
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5.
Activation of Notch-1 signaling maintains the neoplastic phenotype in human Ras-transformed cells 总被引:27,自引:0,他引:27
Weijzen S Rizzo P Braid M Vaishnav R Jonkheer SM Zlobin A Osborne BA Gottipati S Aster JC Hahn WC Rudolf M Siziopikou K Kast WM Miele L 《Nature medicine》2002,8(9):979-986
Truncated Notch receptors have transforming activity in vitro and in vivo. However, the role of wild-type Notch signaling in neoplastic transformation remains unclear. Ras signaling is deregulated in a large fraction of human malignancies and is a major target for the development of novel cancer treatments. We show that oncogenic Ras activates Notch signaling and that wild-type Notch-1 is necessary to maintain the neoplastic phenotype in Ras-transformed human cells in vitro and in vivo. Oncogenic Ras increases levels and activity of the intracellular form of wild-type Notch-1, and upregulates Notch ligand Delta-1 and also presenilin-1, a protein involved in Notch processing, through a p38-mediated pathway. These observations place Notch signaling among key downstream effectors of oncogenic Ras and suggest that it might be a novel therapeutic target. 相似文献
6.
Sulfated homologues of heparin inhibit hepatitis C virus entry into mammalian cells 总被引:1,自引:0,他引:1 下载免费PDF全文
The mechanism of entry of hepatitis C virus (HCV) through interactions between the envelope glycoproteins and specific cell surface receptors remains unclear at this time. We have previously shown with the vesicular stomatitis virus (VSV)/HCV pseudotype model that the hypervariable region 1 of the HCV E2 envelope glycoprotein helps in binding with glycosaminoglycans present on the cell surface. In this study, we have examined the binding of HCV envelope glycoproteins with chemically modified derivatives of heparin. Furthermore, we have determined the functional relevance of the interaction of heparin derivatives with HCV envelope glycoproteins for infectivity by using a human immunodeficiency virus (HIV)/HCV pseudotype, a VSV/HCV pseudotype, and cell culture-grown HCV genotype 1a. Taken together, our results suggest that the HCV envelope glycoproteins rely upon O-sulfated esters of a heparin homologue to facilitate entry into mammalian cells. 相似文献
7.
Aster Gebrekirstos Meine van Noordwijk Henry Neufeldt Ralph Mitl?hner 《Trees - Structure and Function》2011,25(1):95-102
The relationships between annual wood stable carbon isotope composition (δ13C), dry season midday plant water potential, and annual growth rate were investigated to asses the ability of agroforestry
species to adapt to climate changes. 6–8 stem disks from four co-occurring species (Acacia senegal, A. seyal, A. tortilis and Balanites aegyptiaca) were collected for radial growth measurements using tree-ring analysis spanning 1930–2003. Annual δ13C was measured on three tree disks per species for the period 1970–2002. Midday plant water potential was measured during
the dry season. Annual radial growth and midday plant water potential ranged from 0.27 to 9.12 mm and −1.0 to −5.0 MPa, respectively,
with statistically significant differences. After correcting annual wood δ13C for atmospheric changes in δ13C, carbon isotopic composition ranged from −22.22 to −26.58‰. Relationships between δ13C, radial growth and plant water potentials revealed the interaction of water availability, stomatal conductance, δ13C values and growth. Two contrasting water use strategies and competitive advantages can be distinguished. Species with lower
mean δ13C values (A. senegal and A. seyal) show high plant water potential and, hence, better growth during moist years. Thus, they indicate low water use efficiency
(WUE) and opportunistic water use strategy. On the other hand, species with lower water potentials (A. tortilis and B. aegyptiaca) showed relative better growth performance and less increase in δ13C in drought years, reflecting their high WUE and conservative water use strategy. These results suggest that δ13C in tree rings can be useful in estimating historic changes in plant WUE and hence in screening drought tolerant species
in the face of expected climate changes, as well as for assessing the functional diversity and risk reduction in mixed vegetation. 相似文献
8.
Tiyanont K Wales TE Aste-Amezaga M Aster JC Engen JR Blacklow SC 《Structure (London, England : 1993)》2011,19(4):546-554
Notch proteins are transmembrane receptors that normally adopt a resting state poised to undergo activating proteolysis upon ligand engagement. Receptor quiescence is maintained by three LIN12/Notch repeats (LNRs), which wrap around a heterodimerization domain (HD) divided by furin cleavage at site S1 during maturation. Ligand binding initiates signaling by inducing sensitivity of the HD to proteolysis at the regulated S2 cleavage site. Here, we used hydrogen exchange mass spectrometry to examine the solution dynamics of the Notch1 negative regulatory region in autoinhibited states before and after S1 cleavage, in a proteolytically sensitive "on" state, and in a complex with an inhibitory antibody. Conversion to the "on" state leads to accelerated deuteration in the S2 region and in nearby secondary structural elements within the HD. In contrast, complexation with the inhibitory antibody retards deuteration around the S2 site. Together, these studies reveal how S2 site exposure is promoted by receptor activation and suppressed by inhibitory antibodies. 相似文献
9.
Recent deep sequencing of cancer genomes has produced an explosion of new data implicating Notch signaling in several human cancers. Unlike most other pathways, these data indicate that Notch signaling can be either oncogenic or tumor suppressive, depending on the cellular context. In some instances, these relationships were predicted from mouse models or presaged by developmental roles for Notch, but in other cases were unanticipated. This review discusses the pathogenic and translational significance of these new findings. 相似文献
10.
Notch signaling is a direct determinant of keratinocyte growth arrest and entry into differentiation 总被引:37,自引:0,他引:37