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151.
Moreno E; Lanne B; Vazquez AM; Kawashima I; Tai T; Fernandez LE; Karlsson KA; Angstrom J; Perez R 《Glycobiology》1998,8(7):695-705
P3 is a mouse monoclonal antibody (mAb) that binds to several NeuGc-
containing gangliosides. It also reacts with antigens expressed in human
breast tumors (Vazquez et al. (1995) Hybridoma , 14, 551-556). In this
work, the binding specificity of P3 has been characterized in more detail
using a panel of glycolipids that included several disialylated
gangliosides and several chemical derivatives of NeuGc-GM3. The carboxyl
group and the nitrogen function of sialic acid were found to play important
roles in the antibody binding, whereas the glycerol tail appears to be
nonrelevant. Molecular modeling was used to analyze the binding data,
including the finding that P3 selectively recognizes the internal NeuGc in
GD3. For this purpose, conformational studies of GD3 were performed using
molecular dynamics. It was concluded that sialic acid binds the P3 antibody
through its upper face (the one on which the carboxyl group is exposed) and
the C4-C5 side of the sugar ring, whereas none or very little contact
between the galactose residue and the protein is evident. Conformational
analysis of GD3 revealed that, despite the large flexibility of the
NeuGcalpha8NeuGc linkage, the P3 binding epitope on the external sialic
acid is not well exposed for any of the possible conformations this linkage
can adopt, whereas the internal sialic acid presents the epitope in a
proper way for several of these conformations. As a final result, a
coherent picture of the epitope that fits the wide binding data was
obtained.
相似文献
152.
153.
Maria Benitez‐Guijarro Cesar Lopez‐Ruiz Žygimantė Tarnauskaitė Olga Murina Mahwish Mian Mohammad Thomas C Williams Adeline Fluteau Laura Sanchez Raquel Vilar‐Astasio Marta Garcia‐Canadas David Cano Marie‐Jeanne HC Kempen Antonio Sanchez‐Pozo Sara R Heras Andrew P Jackson Martin AM Reijns Jose L Garcia‐Perez 《The EMBO journal》2018,37(15)
154.
Immunological similarities between specific chloroplast ribosomal proteins from Chlamydomonas reinhardtii and ribosomal proteins from Escherichia coli 总被引:11,自引:0,他引:11
Polyclonal antibodies were elicited against seven of the 33 different
proteins of the large subunit of the chloroplast ribosome from
Chlamydomonas reinhardtii. Three of these proteins are synthesized in the
chloroplast and four are made in the cytoplasm and imported. In western
blots, six of the seven antisera are monospecific for their respective
large subunit ribosomal proteins, and none of these antisera cross-reacted
with any chloroplast small subunit proteins from C. reinhardtii. Antisera
to the three chloroplast-synthesized ribosomal proteins cross-reacted with
specific Escherichia coli large subunit proteins of comparable charge and
molecular weight. Only one of the four antisera to the chloroplast
ribosomal proteins synthesized in the cytoplasm cross-reacted with an E.
coli large subunit protein. None of the antisera cross-reacted with any E.
coli small subunit proteins. On the assumption of a procaryotic,
endosymbiotic origin for the chloroplast, those chloroplast ribosomal
proteins still synthesized within the organelle appear to have retained
more antigenic sites in common with E. coli ribosomal proteins than have
those which are now the products of cytoplasmic protein synthesis. Antisera
to this cytoplasmically synthesized group of chloroplast ribosomal proteins
did not recognize any antigenic sites among C. reinhardtii cytoplasmic
ribosomal proteins, suggesting that the genes for the cytoplasmically
synthesized chloroplast ribosomal proteins either are not derived from the
cytoplasmic ribosomal protein genes or have evolved to a point where no
antigenic similarities remain.
相似文献
155.
Marie-Elisabeth Samson-Bouma Nicole Verthier Leo A Ginsel Grard Feldmann Jack AM Fransen Lawrence P Aggerbeck 《Biology of the cell / under the auspices of the European Cell Biology Organization》1996,87(3):189-196
Summary— Intestinal biopsies from patients having genetic disorders of lipoprotein assembly and secretion, such as abetalipoproteinemia (ABL) or Anderson's disease (AD), contain large amounts of lipids which are accumulated in the enterocytes. Determination of the intracellular sites in which the lipids accumulate and to which apolipoproteins the lipids are bound would help to identify the defects in these diseases and further elucidate the mechanisms by which lipoprotein assembly and secretion occur normally. Ultrastructural immunogold labeling, however, is hampered by the poor preservation of the lipids accumulated in the enterocytes of these patients. We have used routine electron microscopy (fixation and ultra-thin sectioning) along with three methods for immunogold labeling of lipid-laden enterocytes; ultrathin cryosectioning, low temperature freeze substitution with embedding in Lowicryl K4M, and ultra-low temperature freeze substitution with embedding in Lowicryl HM20, to establish a protocol for investigating the intestinal tissue from these patients. Ultracryosectioning, while preserving the overall morphology of the lipid laden enterocytes, did not preserve the lipid content and the immunogold labeling of apolipoprotein B (ApoB) appeared dislocated. Freeze substitution and low temperature embedding in Lowicryl K4M, in contrast, appeared to better preserve the lipid and lipoprotein structures; however, the antigenicity of both apoAI and apoB appeared to be lost and no specific labeling could be obtained. Freeze substitution and embedding in Lowicryl HM20 best preserved the lipid and lipoprotein structures while maintaining apoprotein antigenicity. In conclusion, immunogold labeling of apolipoproteins on lipid structures in the lipid-laden enterocytes of patients with ABL and AD is best obtained by freeze substitution and embedding in Lowicryl HM20. 相似文献
156.
Evidence for effect of random genetic drift on G+C content after lateral transfer of fucose pathway genes to Escherichia coli K-12 总被引:4,自引:0,他引:4
The cps cluster of Escherichia coli K-12 comprises genes involved in
synthesis of capsular polysaccharide colanic acid. Part of the E. coli K-12
cps region has been cloned and sequenced and compared to its Salmonella
enterica LT2 counterpart. The cps genes from the two organisms are
homologous; in the case of the LT2 genes, with G+C content of 0.61 and
codons characteristic of high G+C species, it seems clear that they have
been acquired relatively recently by lateral transfer from a high G+C
species. The K-12 form of these cps genes is closely related to those of
LT2 so must derive from the same high G+C species, but it appears to have
transferred much earlier such that random genetic drift has brought P3 (the
corrected G+C content of codon base 3) down from 0.77 to 0.64, more than
halfway to the E. coli average of 0.57. We estimate, using an equation
developed by Sueoka, that the lateral transfer to E. coli took place
approximately 45 million years ago. This is the first report we are aware
of demonstrating the expected adjustment of P3 after lateral transfer
between species with different G+C content DNA.
相似文献
157.
Background
Intestinal threadworm Strongyloides stercoralis is a parasite of dog, cat and primates that occurs worldwide being most prevalent in tropical and subtropical countries. The adult parasitic worm is about 2 mm long and slender. It possesses both parasitic and free-living lifecycles. The parasitic worms are females. Strongyloides stercoralis infects the host via percutaneous, peroral or transmammary transmission in addition to autoinfection. Clinical disease varies from inapparent to severe enteritis and pneumonia. The diagnosis is based on demonstration of larvae in fresh faeces, which is best made by Baermann technique. 相似文献158.
James GD Prendergast Harry Campbell Nick Gilbert Malcolm G Dunlop Wendy A Bickmore Colin AM Semple 《BMC evolutionary biology》2007,7(1):72
Background
Evolutionary rates are not constant across the human genome but genes in close proximity have been shown to experience similar levels of divergence and selection. The higher-order organisation of chromosomes has often been invoked to explain such phenomena but previously there has been insufficient data on chromosome structure to investigate this rigorously. Using the results of a recent genome-wide analysis of open and closed human chromatin structures we have investigated the global association between divergence, selection and chromatin structure for the first time. 相似文献159.
Plínio Delatorre Bruno AM Rocha Emmanuel P Souza Taianá M Oliveira Gustavo A Bezerra Frederico BMB Moreno Beatriz T Freitas Tatiane Santi-Gadelha Alexandre H Sampaio Walter F Azevedo Jr Benildo S Cavada 《BMC structural biology》2007,7(1):1-9
Background
Lectins are mainly described as simple carbohydrate-binding proteins. Previous studies have tried to identify other binding sites, which possible recognize plant hormones, secondary metabolites, and isolated amino acid residues. We report the crystal structure of a lectin isolated from Canavalia gladiata seeds (CGL), describing a new binding pocket, which may be related to pathogen resistance activity in ConA-like lectins; a site where a non-protein amino-acid, α-aminobutyric acid (Abu), is bound.Results
The overall structure of native CGL and complexed with α-methyl-mannoside and Abu have been refined at 2.3 Å and 2.31 Å resolution, respectively. Analysis of the electron density maps of the CGL structure shows clearly the presence of Abu, which was confirmed by mass spectrometry.Conclusion
The presence of Abu in a plant lectin structure strongly indicates the ability of lectins on carrying secondary metabolites. Comparison of the amino acids composing the site with other legume lectins revealed that this site is conserved, providing an evidence of the biological relevance of this site. This new action of lectins strengthens their role in defense mechanisms in plants. 相似文献160.