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81.
82.
Jagjeet S. Mnpotra Zhuanhong Qiao Jian Cai Diane L. Lynch Alan Grossfield Nicholas Leioatts Dow P. Hurst Michael C. Pitman Zhao-Hui Song Patricia H. Reggio 《The Journal of biological chemistry》2014,289(29):20259-20272
In this study, we applied a comprehensive G protein-coupled receptor-Gαi protein chemical cross-linking strategy to map the cannabinoid receptor subtype 2 (CB2)- Gαi interface and then used molecular dynamics simulations to explore the dynamics of complex formation. Three cross-link sites were identified using LC-MS/MS and electrospray ionization-MS/MS as follows: 1) a sulfhydryl cross-link between C3.53(134) in TMH3 and the Gαi C-terminal i-3 residue Cys-351; 2) a lysine cross-link between K6.35(245) in TMH6 and the Gαi C-terminal i-5 residue, Lys-349; and 3) a lysine cross-link between K5.64(215) in TMH5 and the Gαi α4β6 loop residue, Lys-317. To investigate the dynamics and nature of the conformational changes involved in CB2·Gi complex formation, we carried out microsecond-time scale molecular dynamics simulations of the CB2 R*·Gαi1β1γ2 complex embedded in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer, using cross-linking information as validation. Our results show that although molecular dynamics simulations started with the G protein orientation in the β2-AR*·Gαsβ1γ2 complex crystal structure, the Gαi1β1γ2 protein reoriented itself within 300 ns. Two major changes occurred as follows. 1) The Gαi1 α5 helix tilt changed due to the outward movement of TMH5 in CB2 R*. 2) A 25° clockwise rotation of Gαi1β1γ2 underneath CB2 R* occurred, with rotation ceasing when Pro-139 (IC-2 loop) anchors in a hydrophobic pocket on Gαi1 (Val-34, Leu-194, Phe-196, Phe-336, Thr-340, Ile-343, and Ile-344). In this complex, all three experimentally identified cross-links can occur. These findings should be relevant for other class A G protein-coupled receptors that couple to Gi proteins. 相似文献
83.
G. Lawrance R. J. Rylett †P. M. Richardson †R. J. Dunn ‡K. E. Dow R. J. Riopelle 《Journal of neurochemistry》1995,64(4):1483-1490
Abstract: In the human neuroblastoma cell line LA-N-2, recombinant rat ciliary neurotrophic factor (CNTF) induced neurite growth and cholinergic differentiation that were both half-maximally saturated at <100 p M of the neurokine, but was not required for cell survival in serum-free conditions over a 13-day period. CNTF markedly stimulated choline acetyltransferase activity and acetylcholine synthesis, whereas high-affinity choline transport was only slightly enhanced and acetylcholinesterase activity was unchanged. Leukemia inhibitory factor had effects identical to CNTF on neurite growth and choline acetyltransferase activity, but interleukin 6 had no effect. Radioiodinated CNTF binding and affinity cross-linking studies were consistent with tripartite receptor activation as a mediator of the observed biological effects. 相似文献
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Communication with a growing family: diffusible signal factor (DSF) signaling in bacteria 总被引:1,自引:0,他引:1
Many pathogenic bacteria use cell-cell signaling to regulate the expression of factors contributing to virulence. Bacteria produce signals of diverse structural classes. The signal molecule known as diffusible signal factor (DSF) is a cis-unsaturated fatty acid that was first described in the plant pathogen Xanthomonas campestris. Recent work has shown that structurally related molecules produced by the unrelated bacteria Burkholderia cenocepacia and Pseudomonas aeruginosa regulate virulence, biofilm formation and antibiotic tolerance in these important human pathogens. Furthermore, DSF family signals have been shown to be involved in interspecies signaling that modulates bacterial behavior. An understanding of these diverse signaling mechanisms could suggest strategies for interference, with consequences for disease control. 相似文献
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C J Dow J E Dumont P Ketelbant 《Comptes rendus des séances de la Société de biologie et de ses filiales》1986,180(6):629-632
The proportions of various cells types were studied in the thyroids of a variety of dogs used for laboratory experiments. A remarkable constancy was found with epithelial cells accounting for 70% of the total number of cells. The relative proportions of luminal and epithelial cells spaces were also very similar in different animals (47% and 26% respectively). 相似文献
90.
Julian A.T. Dow 《Journal of insect physiology》1981,27(9):579-585
Using amaranth dye as a marker solute, the movements of fluids in the gut of Schistocerca gregaria was studied, either by feeding a meal containing the dye or by injecting the dye into the haemolymph, and by comparing the distribution of amaranth with those of naturally-occurring solutes in the alimentary tract.In animals deprived of food for more than 2–4 hr, some of the fluid from the Malpighian tubules moves forward through the solid food matrix in the midgut carrying solutes into the anterior midgut and gastric caeca, where water is absorbed. After a meal the crop empties at a rate which saturates the absorptive capacity of the anterior caeca, producing a net movement of fluid down the midgut and so such a countercurrent system is not observed in animals fed ad lib., where dye introduced into the gut always moves posteriorly.A countercurrent fluid movement confers several advantages on the alimentary system which act to maximise the efficiency of nutrient absorption: the principal disadvantage of the countercurrent system is that noxious solutes, as well as nutrients, will accumulate at high concentrations near the permeable site of nutrient uptake. Thus a countercurrent flow of solutes is observed only when the insect is deprived of food and the need to conserve nutrient resources exceeds that of excretion of noxious substances. Ways in which the site of nutrient absorption may be protected from noxious solutes are discussed.The anterior caeca gradually become bloated with dark fluid as digestion proceeds; this is expelled into the midgut when a fresh meal is ingested. 相似文献