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排序方式: 共有913条查询结果,搜索用时 46 毫秒
1.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
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M R Wessels V Pozsgay D L Kasper H J Jennings 《The Journal of biological chemistry》1987,262(17):8262-8267
We have derived oligosaccharides from the capsular polysaccharide of type III group B Streptococcus by enzymatic hydrolysis of a specific backbone glycosidic bond utilizing an endo-beta-galactosidase from Flavobacterium keratolyticus. Enzymatic digestion of the polysaccharide produced oligosaccharide fragments of one or more pentasaccharide repeating units. On the basis of 13C NMR, 1H NMR, and methylation analyses, it was established that the smallest digestion fragment was alpha-D-NeupNAc-(2----3)-beta-D-Galp-(1----4)-[beta-D-Glcp-(1----6 )]- beta-D-GlcpNAc-(1----3)-beta-D-Gal. The isolation of this oligosaccharide is consistent with the susceptibility of the beta-D-Galp-(1----4)-beta-D-Glcp linkage in the backbone of the type III group B streptococcal polysaccharide and confirms that the polysaccharide is composed of a pentasaccharide repeating unit. High resolution 13C NMR spectroscopic studies indicated that, as in the case of the pentasaccharide, the terminal sialic acid residues of the type III group B streptococcal polysaccharide were linked to O-3 and not to O-6 of its branch beta-D-galactopyranosyl residues as had been previously reported (Jennings, H. J., Rosell, K.-G., and Kasper, D. L. (1980) Can. J. Chem. 58, 112-120). This linkage was confirmed in an independent methylation analysis of the type III group B streptococcal polysaccharide. Thin layer chromatogram binding assay and radioactive antigen binding assays with radiolabeled oligosaccharides demonstrated the single repeating unit pentasaccharide oligosaccharide to be poorly antigenic. Increasing oligosaccharide size to a decasaccharide consisting of two repeating units resulted in an 8-fold increase in antigen binding in the direct radioactive antigen binding assay. The results suggest that a region of the immunodeterminant site critical for antibody binding is located in the backbone of the polysaccharide and involves the beta-D-galactopyranose-(1----4) beta-D-glucopyranose bond. 相似文献
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Signal peptidase can cleave inside a polytopic membrane protein 总被引:3,自引:0,他引:3
The signal peptides of most proteins targeted to the endoplasmic reticulum are specifically cleaved by signal peptidase. Although potential cleavage sites occur frequently in polytopic proteins after membrane-spanning segments, processing is restricted to the first hydrophobic domain, suggesting that signal peptidase might not have access to subsequently translocated, internal domains. To test this hypothesis, we replaced the third transmembrane segment of an artificial threefold membrane-spanning protein by a sequence which is normally an amino-terminal signal. Upon in vitro translation and insertion into microsomes, efficient cleavage at this sequence was observed, thus demonstrating the ability of signal peptidase to cleave within polytopic membrane proteins. 相似文献
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Rapid detection of chromosome 16 inversion in acute nonlymphocytic leukemia, subtype M4: regional localization of the breakpoint in 16p 总被引:4,自引:0,他引:4
J G Dauwerse T Kievits G C Beverstock D van der Keur E Smit H W Wessels A Hagemeijer P L Pearson G J van Ommen M H Breuning 《Cytogenetics and cell genetics》1990,53(2-3):126-128
The pericentric inversion of chromosome 16 characteristic for acute nonlymphocytic leukemia, subtype M4, was detected in five patients by means of nonradioactive in situ hybridization of complete cosmids. First, five cosmids situated along the short arm of chromosome 16 were used to map the breakpoint of the inversion distal to the rare folate-sensitive fragile site FRA16A. Then, the use of two cosmids on either side of the breakpoint, combined with a probe specific for the centromeric region of chromosome 16, readily detected the inversion, even in poor metaphase spreads. 相似文献
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Insertion of a multispanning membrane protein occurs sequentially and requires only one signal sequence 总被引:26,自引:0,他引:26
To study the insertion of multispanning membrane proteins into the endoplasmic reticulum, we constructed novel proteins on the cDNA level by repeating, up to four times, the internal signal-anchor domain of the asialoglycoprotein receptor H1. Upon in vitro translation in the presence of microsomes, these polypeptides are indeed inserted as polytopic membrane proteins. The first hydrophobic domain functions as a signal and the second as a stop-transfer sequence, while the third initiates a second translocation process, halted again by the fourth. We were able to demonstrate that insertion occurs sequentially, starting with the first apolar segment from the amino terminus. By replacing the original signal-anchor domains by a mutant sequence not recognized by signal recognition particle (SRP), it was shown that only the first hydrophobic domain needs to be a signal sequence and that the second translocation event does not require SRP. 相似文献
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Nurit Eyal Nurit Firon Sylvia Wilder Edwin H. Kolodny Mia Horowitz 《Human genetics》1991,87(3):328-332
Summary Single-stranded cDNA was prepared from RNA obtained from a patient with type 1 Gaucher disease. The cDNA was amplified in vitro and analyzed by sequencing. Three base-pair changes were identified which included a G to C transversion at nucleotide 3119 of the active gene (Asp140His), an A to C transversion at nucleotide 3170 (Lys157Gln) and a G to A change at nucleotide 5309 (Glu326Lys). To study the mode of inheritance of the three different base-pair changes, genomic DNA was prepared from blood or skin fibroblasts of several family members. Genomic glucocerebrosidase DNA sequences were amplified and subjected to hybridization with allele-specific oligonucleotides (ASOs). The hybridization profiles demonstrated that two of the basepair changes originated from the mother and were transmitted to her two affected sons and to a grandchild, while the third base-pair change, originating from the father, was transmitted to his two affected sons, a carrier daughter and a second grandchild. Tests of other patients with Gaucher disease failed to disclose the presence of the three base-changes. This is a unique family with three base-pair changes tightly linked to Gaucher disease. 相似文献