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1.
Zlatka Kostova Benjamin C Yan Saulius Vainauskas Roberta Schwartz Anant K Menon Peter Orlean 《European journal of biochemistry》2003,270(22):4507-4514
Saccharomyces cerevisiae Gpi3p is the UDP-GlcNAc-binding and presumed catalytic subunit of the enzyme that forms GlcNAc-phosphatidylinositol in glycosylphosphatidylinositol biosynthesis. It is an essential protein with an EX7E motif that is conserved in four families of retaining glycosyltransferases. All Gpi3ps contain a cysteine residue four residues C-terminal to EX7E. To test their importance for Gpi3p function in vivo, Glu289 and 297 in the EX7E motif of S. cerevisiae Gpi3p, as well as Cys301, were altered by site-specific mutagenesis, and the mutant proteins tested for their ability to complement nonviable GPI3-deleted haploids. Gpi3p-C301A supported growth but membranes from C301A-expressing cells had low in vitro N-acetylglucosaminylphosphatidylinositol (GlcNAc-PI) synthetic activity. Haploids harboring Gpi3p-E289A proved viable, although slow growing but Gpi3-E297A did not support growth. The E289D and E297D mutants both supported growth at 25 degrees C, but, whereas the E289D strain grew at 37 degrees C, the E297D mutant did not. Membranes from E289D mutants had severely reduced in vitro GlcNAc-PI synthetic activity and E297D membranes had none. The mutation of the first Glu in the EX7E motif of Schizosaccharomyces pombe Gpi3p (Glu277) to Asp complemented the lethal null mutation in gpi3+ and supported growth at 37 degrees C, but the E285D mutant was nonviable. Our results suggest that the second Glu residue of the EX7E motif in Gpi3p is of greater importance than the first for function in vivo. Further, our findings do not support previous suggestions that the first Glu of an EX7E protein is the nucleophile and that Cys301 has an important role in UDP-GlcNAc binding by Gpi3ps. 相似文献
2.
Ferdinand Bohlmann Karl-Heinz Knoll Christa Zdero Pradip Kumar Mahanta Michael Grenz Albert Suwita Dorothea Ehlers Ngo Le Van Wolf-Rainer Abraham Arvind Anant Natu 《Phytochemistry》1977,16(7):965-985
Investigation of about 50 Senecio species has afforded many new substances, in addition to known compounds. Present in these plants are 23 fura 相似文献
3.
Richard Hammerschlag Charles Bakhit Arlene Y. Chiu Anant R. Dravid 《Developmental neurobiology》1977,8(5):439-451
Fast axonal transport of [3H]protein has been examined in bullfrog primary afferent neurons incubated in media supplemented with divalent cations that can act as agonists or antagonists of calcium ions. Incubation in calcium-free medium (CFM) had no effect on the rate of transport, but reduced the amount of transported [3H]protein by 40–60% relative to transport in the contralateral preparation maintained in normal medium. Preparations incubated in CFM supplemented with 1.8 mM SrCl2 (equimolar to the CaCl2 concentration in normal medium) carried out transport at control levels. Incubation conditions in which primary afferent somata were exposed to the Sr2+-medium while nerve trunks were maintained in CFM also supported normal transport. By contrast, selective exposure of nerve trunks to Sr2+-medium, and somata to CFM resulted in a reduced level of transport similar to that observed when the whole preparation was incubated in CFM. The depression of transport resulting from incubation in CFM was shown to be reversible when preparations were transferred from CFM to either Sr2+-supplemented CFM or to normal medium. By contrast to the effects of Sr2+, Ba2+ (up to 18 mM) did not substitute for Ca2+ in the transport process. When normal medium was supplemented with calciumantagonist cations, the amount of transport was depressed (Co2+ > Mn2+ >> Mg2+), with no concomitant effect on the rate of transport. Results of studies with Co2+, as well as those with Sr2+, suggest that a major locus of action of these cations is within the neuronal soma at a step subsequent to protein synthesis, and prior to the onset of protein translocation via the transport system. Thus, it is inferred that these divalent cations affect a calcium-dependent step that occurs during the initiation phase of fast axonal transport. 相似文献
4.
Yadav Jyoti Verma Anoop Kumar Ahmad Md. Kaleem Garg Ravindra K. Shiuli Mahdi Abbas Ali Srivastava Shrikant 《Molecular biology reports》2021,48(4):3245-3252
Molecular Biology Reports - Alzheimer's disease is a common neurodegenerative disease in the elderly population and a leading cause of dementia. Genetics and environmental risk factors were... 相似文献
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6.
Alexander G. Georgiev Jesper Johansen Vidhya D. Ramanathan Yves Y. Sere Christopher T. Beh Anant K. Menon 《Traffic (Copenhagen, Denmark)》2013,14(8):912-921
The pan‐eukaryotic endoplasmic reticulum (ER) membrane protein Arv1 has been suggested to play a role in intracellular sterol transport. We tested this proposal by comparing sterol traffic in wild‐type and Arv1‐deficient Saccharomyces cerevisiae. We used fluorescence microscopy to track the retrograde movement of exogenously supplied dehydroergosterol (DHE) from the plasma membrane (PM) to the ER and lipid droplets and high performance liquid chromatography to quantify, in parallel, the transport‐coupled formation of DHE esters. Metabolic labeling and subcellular fractionation were used to assay anterograde transport of ergosterol from the ER to the PM. We report that sterol transport between the ER and PM is unaffected by Arv1 deficiency. Instead, our results indicate differences in ER morphology and the organization of the PM lipid bilayer between wild‐type and arv1Δ cells suggesting a distinct role for Arv1 in membrane homeostasis. In arv1Δ cells, specific defects affecting single C‐terminal transmembrane domain proteins suggest that Arv1 might regulate membrane insertion of tail‐anchored proteins involved in membrane homoeostasis . 相似文献
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Ariopsis macrosperma sp. nov. from Western Ghats of Maharashtra, India, is described and illustrated. It differs from the other two species in the genus, A. peltata and A. protanthera, in having a typical terrestrial habit, growing on the soil as undergrowth below the forest canopy, thick, leathery leaves and lower number of larger, ovoid and ribbed seeds. 相似文献
9.
In this study, we have evaluated cerebral atrophy, neurometabolite homeostasis, and neural energetics in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridin (MPTP) model of Parkinson's disease. In addition, the efficacy of acute l ‐DOPA treatment for the reversal of altered metabolic functions was also evaluated. Cerebral atrophy and neurochemical profile were monitored in vivo using MRI and 1H MR Spectroscopy. Cerebral energetics was studied by 1H‐[13C]‐NMR spectroscopy in conjunction with infusion of 13C labeled [1,6‐13C2]glucose or [2‐13C]acetate. MPTP treatment led to reduction in paw grip strength and increased level of GABA and myo‐inositol in striatum and olfactory bulb. 13C Labeling of glutamate‐C4 (1.93 ± 0.24 vs. 1.48 ± 0.06 μmol/g), GABA‐C2 (0.24 ± 0.04 vs. 0.18 ± 0.02 μmol/g) and glutamaine‐C4 (0.26 ± 0.04 vs. 0.20 ± 0.04 μmol/g) from [1,6‐13C2]glucose was found to be decreased with MPTP exposure in striatum as well as in other brain regions. However, glutamine‐C4 labeling from [2‐13C]acetate was found to be increased in the striatum of the MPTP‐treated mice. Acute l ‐DOPA treatment failed to normalize the increased ventricular size and level of metabolites but recovered the paw grip strength and 13C labeling of amino acids from [1,6‐13C2]glucose and [2‐13C]acetate in MPTP‐treated mice. These data indicate that brain energy metabolism is impaired in Parkinson's disease and acute l ‐DOPA therapy could temporarily recover the cerebral metabolism.
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