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91.
Asensio JL; Canada FJ; Bruix M; Gonzalez C; Khiar N; Rodriguez-Romero A; Jimenez-Barbero J 《Glycobiology》1998,8(6):569-577
The specific interaction of hevein with GlcNAc-containing oligosaccharides
has been analyzed by1H-NMR spectroscopy. The association constants for the
binding of hevein to a variety of ligands have been estimated from1H-NMR
titration experiments. The association constants increase in the order
GlcNAc-alpha(1-->6)-Man < GlcNAc < benzyl-beta-GlcNAc <
p-nitrophenyl-beta-GlcNAc < chitobiose < p-
nitrophenyl-beta-chitobioside < methyl-beta-chitobioside <
chitotriose. Entropy and enthalpy of binding for different complexes have
been obtained from van't Hoff analysis. The driving force for the binding
process is provided by a negative DeltaH0which is partially compensated by
negative DeltaS0. These negative signs indicate that hydrogen bonding and
van der Waals forces are the major interactions stabilizing the complex.
NOESY NMR experiments in water solution provided 475 accurate protein
proton-proton distance constraints after employing the MARDIGRAS program.
In addition, 15 unambiguous protein/carbohydrate NOEs were detected. All
the experimental constraints were used in a refinement protocol including
restrained molecular dynamics in order to determine the highly refined
solution conformation of this protein- carbohydrate complex. With regard to
the NMR structure of the free protein, no important changes in the protein
nOe's were observed, indicating that carbohydrate-induced conformational
changes are small. The average backbone rmsd of the 20 refined structures
was 0.055 nm, while the heavy atom rmsd was 0.116 nm. It can be deduced
that both hydrogen bonds and van der Waals contacts confer stability to the
complex. A comparison of the three-dimensional structure of hevein in
solution to those reported for wheat germ agglutinin (WGA) and hevein
itself in the solid state has also been performed. The polypeptide
conformation has also been compared to the NMR-derived structure of a
smaller antifungical peptide, Ac-AMP2.
相似文献
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96.
A mouse model of Waardenburg syndrome type IV resulting from an ENU‐induced mutation in endothelin 3
Ivana Matera Jody L. Cockroft Jennifer L. Moran David R. Beier Dan Goldowitz William J. Pavan 《Pigment cell & melanoma research》2007,20(3):210-215
A line of mutant mice (114‐CH19) exhibiting white spotting and preweaning lethality was identified during an N‐ethyl‐N‐nitrosourea (ENU) mutagenesis screen. The trait segregated as a semidominant bellyspot with reduced penetrance. Homozygous mutant mice showed preweaning lethality, and exhibited white spotting over the majority of the body surface, with pigmented patches remaining around the pinnae, eyes and tail. Linkage analysis localized 114‐CH19 on mouse chromosome 2, suggesting endothelin 3 (Edn3) as a candidate gene. Sequence analysis of Edn3 identified a G > A transversion that encodes an arginine to histidine substitution (R96H). This mutation is predicted to disrupt furin‐mediated proteolytic cleavage of pro‐endothelin that is necessary to form biologically active EDN3. This mutation is novel among human and mouse EDN3 mutants, is the first reported EDN3 ENU mutant, and is the second reported EDN3 point mutation. This study demonstrates the power of using ENU mutagenesis screens to generate new animal models of human disease, and expands the spectrum of EDN3 mutant alleles. 相似文献
97.
Aquaporins (AQP) 1, 2, 3 and 4 belong to the aquaporin water channel family and play an important role in urine concentration by reabsorption of water from renal tubule fluid. Renal AQPs have not been reported in the yak (Bos grunniens), which resides in the Qinghai Tibetan Plateau. We investigated AQPs 1?4 expressions in the kidneys of Yak using immunohistochemical staining. AQP1 was expressed mainly in the basolateral and apical membranes of the proximal tubules and descending thin limb of the loop of Henle. AQP2 was detected in the apical plasma membranes of collecting ducts and distal convoluted tubules. AQP3 was located in the proximal tubule, distal tubule and collecting ducts. AQP4 was located in the collecting ducts, distal straight tubule, glomerular capillaries and peritubular capillaries. The expression pattern of AQPs 1?4 in kidney of yak was different from other species, which possibly is related to kidney function in a high altitude environment. 相似文献
98.
Previous investigations on the monkey kidney COS cell line demonstrated the
weak expression of fucosylated cell surface antigens and presence of
endogenous fucosyltransferase activities in cell extracts. RT-PCR analyses
have now revealed expression of five homologs of human fucosyltransferase
genes, FUT1, FUT4, FUT5, FUT7, and FUT8, in COS cell mRNA. The enzyme in
COS cell extracts acting on unsialylated Type 2 structures is closely
similar in its properties to the alpha1,3- fucosyltransferase encoded by
human FUT4 gene and does not resemble the product of the FUT5 gene.
Although FUT1 is expressed in the COS cell mRNA, it has not been possible
to demonstrate alpha1,2- fucosyltransferase activity in cell extracts but
the presence of Le(y) and blood-group A antigenic determinants on the cell
surface imply the formation of H-precursor structures at some stage. The
most strongly expressed fucosyltransferase in the COS cells is the
alpha1,6-enzyme transferring fucose to the innermost N -acetylglucosamine
unit in N - glycan chains; this enzyme is similar in its properties to the
product of the human FUT8 gene. The enzymes resembling the human FUT4 and
FUT8 gene products both had pH optima of 7.0 and were resistant to 10 mM
NEM. The incorporation of fucose into asialo-fetuin was optimal at 5.5 and
was inhibited by 10 mM NEM. This result initially suggested the presence of
a third fucosyltransferase expressed in the COS cells but we have now shown
that triantennary N- glycans with terminal nonreducing galactose units,
similar to those present in asialo-fetuin, are modified by a weak
endogenous beta-galactosidase in the COS cell extracts and thereby rendered
suitable substrates for the alpha1,6- fucosyltransferase.
相似文献
99.
Rapid, sequential changes in surface morphology of PC12 pheochromocytoma cells in response to nerve growth factor 总被引:20,自引:17,他引:20 下载免费PDF全文
The effect of nerve growth factor (NGF), a substance that promotes the differentiation and maintenance of certain neurons, was studied via scanning electron microscopy utilizing the PC12 clonal NGF-responsive pheochromocytoma cell line. After 2-4 d of exposure to NGF, these cells acquire many of the properties of normal sympathic neurons. However, by phase microscopy, no changes are discernible within the first 12-18 h. Since the primary NGF receptor appears to be a membrane receptor, it seemed likely that some of the initial responses to the factor may be surface related. PC12 cells maintained without NGF are round to ovoid and have numerous microvilli and small blebs. After the addition of NGF, there is a rapidly initiated sequential change in the cell surface. Ruffles appear over the dorsal surface of the cells with 1 min, become prominent by 3 min, and almost disappear by 7 min. Microvilli, conversely, disappear as the dorsal ruffles become prominent. Ruffles are seen at the the periphery of cell at 3 min, are prominent on most of the cells by 7 min and are gone by 15 min. The surface remains smooth from 15 min until 45 min when large blebs appear. The large blebs are present on most cells at 2 h and are gone by 4 h. The surface remains relatively smooth until 6-7 h of NGF treatment, when microvilli reappear as small knobs. These microvilli increase in both number and length to cover the cell surface by 10 h. These changes were not observed with other basic proteins, with α-bungarotoxin (which binds specifically to PC12 membranes), and were not affected by an RNA synthesis inhibitor that blocks initiation of neurite outgrowth. Changes in the cell surface architecture appear to be among the earlist NGF responses yet detected and may represent or reflect primary events in the mechanism of the factor’s action. 相似文献
100.
Stefano Burgio Everly Conway de Macario Alberto JL Macario Francesco Cappello 《Cell stress & chaperones》2021,26(4):611
A few reports suggest that molecular mimicry can have a role in determining the more severe and deadly forms of COVID-19, inducing endothelial damage, disseminated intravascular coagulation, and multiorgan failure. Heat shock proteins/molecular chaperones can be involved in these molecular mimicry phenomena. However, tumor cells can display on their surface heat shock proteins/molecular chaperones that are mimicked by SARS-CoV-2 molecules (including the Spike protein), similarly to what happens in other bacterial or viral infections. Since molecular mimicry between SARS-CoV-2 and tumoral proteins can elicit an immune reaction in which antibodies or cytotoxic cells produced against the virus cross-react with the tumor cells, we want to prompt clinical studies to evaluate the impact of SARS-CoV-2 infection on prognosis and follow up of various forms of tumors. These topics, including a brief historical overview, are discussed in this paper. 相似文献