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Atomic force microscopy study of the rabbit skeletal muscle ryanodine receptors in different functional states

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Science China(Life Sciences) 2002年第3期45卷 225-236页

作者：魏青青程晓阳陈克樱胡钧李民乾朱培闳 Laboratory of Neurobiology Shanghai Institute of Physiology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 200031 China Laboratory of Nuclear Analysis Shanghai Institute of Nucleus Chinese Academy of Sciences Shanghai 200800 China

Atomic force microscope was applied to investigate the effect of extrinsic phospholipid on the structure of rabbit skeletal muscle ryanodine receptor/calcium release channel (RyR1). In addition, in the presence of extrinsic phospholipid, the height and elasticity of the RyR1s in different functional states were also measured. The results indicate: (i) most of the RyR1s showed a normal structure only in the presence of extrinsic phospholipid; (ii) treatment of the RyR1s with AMP and Ca2+ together could increase their Young's Modulus but not change their apparent height; (iii) no detectable change in either height or Young's Modulus of the RyR1s appeared, if the RyR1s were treated with other activators or inhibitors.

关键词： ryanodine receptor/calcium release channel, atomic force microscope, elasticity.

The toxicity test and hypothetical model of Bacillus thuringiensis Cry1Aa helix4

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Science China(Life Sciences) 2002年第6期45卷 561-568页

作者：苏彦辉罗静初朱玉贤曲红张杰 Vachon Vincent Laprade Raynald Groupe de recheche en transport membranaire Universite de MontrealMontrealQuebecCanada

Development of targeted biological agents against agricultural insect pests is of prime importance for the elaboration and implementation of integrated pest management strategies that are environment-friendly, respectful of bio-diversity and safer to human health through reduced use of chemical pesticides. A major goal to understand how Bt toxins work is to elucidate the functions of their three domains. Domains II and III are involved in binding specificity and structural integrity, but the function of Domain I remains poorly understood. Using a Manduca sexta BBMV (brush border membrane vesicles) system, we analyzed its responses to Cry1Aa 15 single-point mutations with altered Domain I helix 4 residues. Light scattering assay showed that toxicity was almost lost in 3 mutants, and we observed significantly reduced toxicity in other 7 mutants. However, 5 mutants retained wild-type toxicity. Using computer software, we simulated the three-dimensional structures of helix 4. Both experimental and bioinformatic analysis showed that residues in Cry1Aa Domain I helix 4 were involved in the formation of ion channels that is critical for its insect toxicity.

关键词： Bt toxin proteins, light scattered assay, ion channel, molecular model.

Effects of BaCl_2 on slow vacuolar ion channels on radish by patch-clamp

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Science China Chemistry 2003年第1期46卷 84-89页

作者：杨频张丽平 Institute of Molecular Science Shanxi University Taiyuan 030006 China

The effects of BaCl_2 on slow vacuolar (SV) currents of radish are studied byusing the whole-vacuolar patch-clamp recording mode. The Ca^(2+)-dependent SV channel can beactivated by cytosolic Ca^(2+). When 1 mmol/L BaCI_2 is added into pipette solution, SV currents aresuppressed remarkably. Then adding BaCI_2 of different concentrations into the bath solution, SVcurrents reflect different effects. The results show that BaCl_2 with a lower concentration (channel currents and the currents are saturated when BaCl_2 concentrations arebetween 1 μmol/L and 1 mmol/L, but BaCl_2 with higher concentration (≥ 3 mmol/L) inhibits SVcurrents.

关键词： patch-clamp, whole-vacuolar recording, slow vacuolar channel, cytosolic Ca2+, Ba2+.