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1.
Catherine Ronin Herman van Halbeek Johannah GM Mutsaers Johannes F G Vliegenthart 《Glycoconjugate journal》1987,4(3):247-254
The lipid-linked precursor ofN-type glycoprotein oligosaccharides was isolated from porcine thyroid microsomes after in cubation with UDP[3H] Glucose. The carbohydrate was released from dolichol pyrophosphate by mild acid hydrolysis, purified by gel filtration and characterized by 500-MHz1H-NMR spectroscopy in combination with enzymatic degradation. The parent oligosaccharide was found to be Glc3Man9Glc-NAc2. The three glucose residues are present in the linear sequence Glcα1-2Glα1-3 Glc, the latter being α(1-3)-linked to one of the mannose residues. In order to establish the branch location of the triglucosyl unit, the parent compound was digested with jack-bean α-mannosidase. The oligosaccharide product was purified by gel filtration, and identified by1H-NMR as Glc3Man5GlcNAc2 lacking the mannose residues A, D2, B and D3. Therefore, the structure of the precursor oligosaccharide is as follows: $$\begin{gathered} c b a D_1 C 4 \hfill \\ Glc\alpha 1 - 2Glc\alpha 1 - 3Glc\alpha 1 - 3Man\alpha 1 - 2Man\alpha 1 - 2Man\alpha 1 \hfill \\ 3 \swarrow 3 2 1 \hfill \\ Man\alpha 1 - 2Man\alpha 1 Man\beta 1 - 4GlcNAc\beta 1 - 4GlcNAc \hfill \\ D_{2 } A 3 6 \hfill \\ Man\alpha 1 \hfill \\ 6 \hfill \\ Man\alpha 1 - 2Man\alpha 1 \nwarrow 4 \hfill \\ D_3 B \hfill \\ \end{gathered} $$ 相似文献
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Early and late periodic patterns of even skipped expression are controlled by distinct regulatory elements that respond to different spatial cues 总被引:14,自引:0,他引:14
We have identified the regulatory sequences required for the periodic expression of the Drosophila pair rule gene even skipped (eve). We find that the gradually changing pattern of periodic eve expression during early embryogenesis is directed by two distinct regulatory programs. Initially, eve expression in individual stripes is established by different regulatory elements, each of which responds to nonperiodic spatial cues provided, at least in part, by the gap genes. Later, coordinate expression of eve in all seven stripes is directed by a single regulatory region that responds to periodic cues provided by primary pair rule genes, including eve itself. As a consequence of this two-step regulatory program, eve functions both in the establishment of the periodic pattern of gene expression and in the subsequent specification of parasegmental boundaries. 相似文献
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Correct developmental expression of a cloned alcohol dehydrogenase gene transduced into the Drosophila germ line 总被引:59,自引:0,他引:59
We have used P-element-mediated transformation to introduce a cloned Drosophila alcohol dehydrogenase (Adh) gene into the germ line of ADH null flies. Six independent transformants expressing ADH were identified by their acquired resistance to ethanol. Each transformant carries a single copy of the cloned Adh gene in a different chromosomal location. Four of the six transformant lines exhibit normal Adh expression by the following criteria: quantitative levels of ADH enzyme activity in larvae and adults; qualitative tissue specificity; the size of stable Adh mRNA; and the characteristic developmental switch in utilization of two different Adh promoters. The remaining two transformants express ADH enzyme activity with the correct tissue specificity, but at a lower level than wild type. These results demonstrate that an 11.8 kb chromosomal fragment containing the Adh gene includes the cis-acting sequences necessary for its correct developmental expression, and that a variety of chromosomal sites permit proper Adh gene function. 相似文献
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Human β-globin mRNA precursors (pre-mRNAs) synthesized in vitro from a bacteriophage SP6 promoter/β-globin gene fusion are accurately and efficiently spliced when added to a HeLa cell nuclear extract. Under optimal conditions, the first intervening sequence (IVS 1) is removed by splicing in up to 90% of the input. pre-mRNA. Splicing requires ATP and in its absence the pre-mRNA is neither spliced nor cleaved at splice junctions. Splicing does not require that the pre-mRNA contain a correct 5′ or 3′ end, a 3′ poly A tail, or a 5′-terminal cap structure. However, capping of the pre-mRNA significantly affects the specificity of in vitro processing. In the absence of a cap approximately 30%–40% of the pre-mRNA is accurately spliced, and a number of aberrantly cleaved RNAs are also detected. In contrast, capped pre-mRNAs are spliced more efficiently and produce fewer aberrant RNA species. The specificity of splice-site selection in vitro was tested by analyzing pre-mRNAs that contain β-thalassemia splicing mutations in IVS 1. Remarkably, these mutations cause the same abnormal splicing events in vitro and in vivo. The ability to synthesize mutant pre-mRNAs and study their splicing in a faithful in vitro system provides a powerful approach to determine the mechanisms of RNA splice-site selection. 相似文献
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Single-cell multi-omics assays offer unprecedented opportunities to explore epigenetic regulation at cellular level. However, high levels of technical noise and data sparsity frequently lead to a lack of statistical power in correlative analyses, identifying very few, if any, significant associations between different molecular layers. Here we propose SCRaPL, a novel computational tool that increases power by carefully modelling noise in the experimental systems. We show on real and simulated multi-omics single-cell data sets that SCRaPL achieves higher sensitivity and better robustness in identifying correlations, while maintaining a similar level of false positives as standard analyses based on Pearson and Spearman correlation. 相似文献
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