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51.
Abnormal binding of spectrin to the membrane of erythrocytes in some cases of hereditary spherocytosis 总被引:2,自引:0,他引:2
In two cases of hereditary spherocytosis that we have examined, spectrin was bound abnormally tightly to the erythrocyte membrane, and could not be released by low ionic strength dialysis. This type of behaviour occurs in normal red cells only after heating above 50 degrees C. It appears that some cases of spherocytosis may be due to the presence of a protein which is abnormally temperature sensitive. 相似文献
52.
Studies on the turnover of mouse brain synaptosomal proteins 总被引:1,自引:1,他引:0
(l) The half-lives of the proteins of various fractions of whole mouse brain increase with increasing insolubility; the supernatant and hypotonic-extractable proteins had half-lives of about 13 days, whereas the membrane proteins solubilized with Triton X-100 and SLS had half-lives of about 18 days. The proteins of the subfractions of synaptosomes had half-lives ranging from 15 to 19 days; those in the cytoplasm had a half-life of 18·3 days, in the membranes, about 17 days and in the synaptic vesicles, 15·6 days. (2) Although the half-life of the synaptic vesicles was not significantly different from that of other synaptosomal subfractions, the vesicles exhibited a different protein pattern on acrylamide gels, an observation which implies that the proteins of the vesicles are qualitatively different from those of other synaptic membranes. (3) The uptake of labelled lysine into the cytoplasm of the synaptosomes of youg mice in vivo was very rapid. (4) The data derived from the relative specific radioactivities of synaptosomal fractions compared with their whole brain analogs support the contention that a sizeable fraction of the synaptosomal cytoplasmic protein was transported to the synapse by axoplasmic flow. The relative specific radioactivities of synaptosomal membrane and synaptic vesicle proteins rose much more quickly than the comparable activities for the cytoplasmic material, and the alternate possibility of synthesis in situ is discussed. 相似文献
53.
The Ca2+- and Mg2+-stimulated ATPase activities present in low ionic strength extracts of erythrocyte membranes have been separated from each other. The Ca2+-ATPase appears to be associated with particulate meterial which could be sedimented by high-speed centrifugation. The pellet obtained was composed mainly of components 1, 2, 4.5, 5 and 7. A soluble protein from the band 3 region, known to be responsible for the Mg2+-ATPase activity, was not detected in this pellet. 相似文献
54.
55.
Nicholas V.C. Ralston Laura J. Raymond 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(11):2405-2416
Background
Methylmercury (CH3Hg+) toxicity is characterized by challenging conundrums: 1) “selenium (Se)-protective” effects, 2) undefined biochemical mechanism/s of toxicity, 3) brain-specific oxidative damage, 4) fetal vulnerability, and 5) its latency effect. The “protective effects of Se” against CH3Hg+ toxicity were first recognized >50?years ago, but awareness of Se's vital functions in the brain has transformed understanding of CH3Hg+ biochemical mechanisms. Mercury's affinity for Se is ~1 million times greater than its affinity for sulfur, revealing it as the primary target of CH3Hg+ toxicity.Scope of review
This focused review examined research literature regarding distinctive characteristics of CH3Hg+ toxicity to identify Se-dependent aspects of its biochemical mechanisms and effects.Conclusions
Research indicates that CH3Hg+ irreversibly inhibits the selenoenzymes that normally prevent/reverse oxidative damage in the brain. Unless supplemental Se is provided, consequences increase as CH3Hg+ approaches/exceeds equimolar stoichiometries with Se, thus forming HgSe and inducing a conditioned Se deficiency. As the biochemical target of CH3Hg+ toxicity, Se-physiology provides perspectives on the brain specificity of its oxidative damage, accentuated fetal vulnerability, and latency. This review reconsiders the concept that Se is a “tonic” that protects against CH3Hg+ toxicity and recognizes Se's role as Hg's molecular “target”. As the most potent intracellular nucleophile, the selenoenzyme inhibition paradigm has broad implications in toxicology, including resolution of conundrums of CH3Hg+ toxicity.General significance
Mercury-dependent sequestration of selenium and the irreversible inhibition of selenoenzymes, especially those required to prevent and reverse oxidative damage in the brain, are primarily responsible for the characteristic effects of mercury toxicity. 相似文献56.
57.
58.
Amiloride does not alter NaCl avoidance in Fischer-344 rats 总被引:2,自引:2,他引:0
Fischer-344 (F-344) rats differ from other common rat strains in that they
fail to show any preference for NaCl at any concentration in two- bottle
preference tests. Because 100 microM amiloride partially blocks the
NaCl-evoked chorda tympani (CT) response in electrophysiological studies,
we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without
100 microM amiloride solution as the solvent. A third group was tested with
unadulterated NaCl solutions following CT transection. Amiloride had no
significant effect on the NaCl preference-aversion function, whereas CT
transection significantly reduced NaCl avoidance. These results suggest
that the amiloride-sensitive component of the NaCl response is not
necessary for F-344 rats to display avoidance of NaCl, but the entire CT
input is.
相似文献
59.
60.
Akhila Bettadapur Samuel S. Hunter Rene L. Suleiman Maura C. Ruyechan Wesley Huang Charles G. Barbieri Hannah W. Miller Tammie S. Y. Tam Matthew L. Settles Katherine S. Ralston 《PLoS pathogens》2021,17(11)
While Entamoeba histolytica remains a globally important pathogen, it is dramatically understudied. The tractability of E. histolytica has historically been limited, which is largely due to challenging features of its genome. To enable forward genetics, we constructed and validated the first genome-wide E. histolytica RNAi knockdown mutant library. This library allows for Illumina deep sequencing analysis for quantitative identification of mutants that are enriched or depleted after selection. We developed a novel analysis pipeline to precisely define and quantify gene fragments. We used the library to perform the first RNAi screen in E. histolytica and identified slow growth (SG) mutants. Among genes targeted in SG mutants, many had annotated functions consistent with roles in cellular growth or metabolic pathways. Some targeted genes were annotated as hypothetical or lacked annotated domains, supporting the power of forward genetics in uncovering functional information that cannot be gleaned from databases. While the localization of neither of the proteins targeted in SG1 nor SG2 mutants could be predicted by sequence analysis, we showed experimentally that SG1 localized to the cytoplasm and cell surface, while SG2 localized to the cytoplasm. Overexpression of SG1 led to increased growth, while expression of a truncation mutant did not lead to increased growth, and thus aided in defining functional domains in this protein. Finally, in addition to establishing forward genetics, we uncovered new details of the unusual E. histolytica RNAi pathway. These studies dramatically improve the tractability of E. histolytica and open up the possibility of applying genetics to improve understanding of this important pathogen. 相似文献