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Li MS, Zheng SQ, Sheng ZH, He SY, Deng QY, Liang C, Wu ZP, Cao FQ, Du M. Determination of Azide Ions in Blood by Pentafluorobenzyl Derivation Followed by GC-MS. Fa Yi Xue Za Zhi 2021; 37:378-381. [PMID: 34379908 DOI: 10.12116/j.issn.1004-5619.2020.300304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Indexed: 11/30/2022]
Abstract
Abstract Objective To establish a method for determination of the azide ions in blood by gas chromatography-mass spectrometry (GC-MS) following pentafluorobenzyl derivatization. Methods A blood sample of 0.2 mL was placed into a 10 mL glass test tube, and the internal standard sodium cyanide, derivatization reagent pentafluorobenzyl bromide and catalyst tetradecyl benzyl dimethyl ammonium chloride were added in turn. After vortex mixing, the mixture was heated with low-power microwave for 3 min. After centrifugation, the organic phase was taken for GC-MS analysis. Results The azide ions in blood had a good linear relationship in the mass concentration range of 0.5 to 20 μg/mL. The lowest detection limit was 0.25 μg/mL and the relative recovery was 91.36%-94.58%. The method was successfully applied to a case of death from sodium azide poisoning. The mass concentration of azide ions in the blood of the dead was 11.11 μg/mL. Conclusion The method developed in this paper has strong specificity and is easy to operate, which is suitable for the rapid detection of azide ions in blood.
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Affiliation(s)
- M S Li
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - S Q Zheng
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - Z H Sheng
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - S Y He
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - Q Y Deng
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - C Liang
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - Z P Wu
- Shanghai Key Laboratory of Crime Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - F Q Cao
- Shanghai Key Laboratory of Crime Scene Evidence, Shanghai Research Institute of Criminal Science and Technology, Shanghai 200083, China
| | - M Du
- Institute of Criminal Science, Jiading Branch of Shanghai Public Security Bureau, Shanghai 201800, China
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He SY, Gong FJ, Lian R, Sheng ZH, Xu JL, Sun WJ, Zheng SQ. Identification of Tiletamine, Zolazepam and Their Metabolites in Drug Facilitated Sexual Assault by GC-QTOF-MS. Fa Yi Xue Za Zhi 2019; 35:581-585. [PMID: 31833293 DOI: 10.12116/j.issn.1004-5619.2019.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Indexed: 06/10/2023]
Abstract
Objective To identify tiletamine, zolazepam and their metabolites in samples from drug facilitated sexual assault by gas chromatography-quadrupole time of flight mass spectrometry (GC-QTOF-MS). Methods Urine samples of victims were collected, and detected by GC-QTOF-MS after liquid-liquid extraction and concentration. The molecular formula of fragments ions was identified by determination of accurate mass numbers, to detect related substances. Results Tiletamine, zolazepam, three metabolites of tiletamine and two metabolites of zolazepam were identified in urine samples from actual cases. Conclusion GC-QTOF-MS provides abundant and accurate information of fragment ions mass numbers, which can be used for qualitative identification of tiletamine, zolazepam and their metabolites in drug facilitated sexual assault.
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Affiliation(s)
- S Y He
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - F J Gong
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - R Lian
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - Z H Sheng
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - J L Xu
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - W J Sun
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
| | - S Q Zheng
- Shanghai Key Laboratory of Criminal Scene Evidence, Institute of Forensic Science of Shanghai Public Security Bureau, Shanghai 200083, China
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3
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Xie LH, Tang SQ, Luo J, Wei XJ, Shao GN, Jiao GA, Sheng ZH, Hu PS. Physiochemical properties of rice starch for production of vermicelli with premium quality. J Food Sci Technol 2017; 54:3928-3935. [PMID: 29085135 DOI: 10.1007/s13197-017-2852-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 09/01/2017] [Accepted: 09/04/2017] [Indexed: 11/28/2022]
Abstract
Rice vermicelli is a main food consumed in China and Southeast Asia. Quality of rice vermicelli varies with rice cultivars. Parameters including amylose content, amylopectin distribution, thermal and pasting characteristics, gel texture and starch granules of three rice cultivars "Zhongjiazao 17", "Xiangzaoxian 24" and "Thai Jasmine Rice", were studied for their impacts on vermicelli quality. Results showed significant differences for the measurements of the quality traits and indicated that a favorable quality of vermicelli was not determined by any single factor instead of a combination of multi-parameters. A vermicelli with a favorable quality could be produced from a rice variety with a high apparent amylose content (>25%), a protein content of 11%, an intermediate gelatinization temperature and gel consistency, and a gel hardness (~3 N for a Rapid Viscosity Analyzer pasting) and moderate retrogradation capacity (a setback viscosity of 30-100 RVU).
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Affiliation(s)
- L H Xie
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - S Q Tang
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - J Luo
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - X J Wei
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - G N Shao
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - G A Jiao
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - Z H Sheng
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
| | - P S Hu
- China National Rice Research Institute, Hangzhou, 310006 People's Republic of China.,China National Center for Rice Improvement/State Key Laboratory of Rice Biology, Hangzhou, 310006 People's Republic of China
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4
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Cui HD, Hu DH, Zhang JN, Gao GH, Zheng CF, Gong P, Xi XH, Sheng ZH, Cai LT. Theranostic gold cluster nanoassembly for simultaneous enhanced cancer imaging and photodynamic therapy. CHINESE CHEM LETT 2017. [DOI: 10.1016/j.cclet.2016.12.038] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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5
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Shi L, Wei XJ, Adedze YMN, Sheng ZH, Tang SQ, Hu PS, Wang JL. Characterization and gene cloning of the rice (Oryza sativa L.) dwarf and narrow-leaf mutant dnl3. Genet Mol Res 2016; 15:gmr8731. [PMID: 27706742 DOI: 10.4238/gmr.15038731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The dwarf and narrow-leaf rice (Oryza sativa L.) mutant dnl3 was isolated from the Japonica cultivar Zhonghua 11 (wild-type). dnl3 exhibited pleiotropic developmental defects. The narrow-leaf phenotype resulted from a marked reduction in the number of vascular bundles, while the dwarf stature was caused by the formation of foreshortened internodes and a reduced number of parenchyma cells. The suggestion that cell division is impaired in the mutant was consistent with the transcriptional behavior of various genes associated with cell division. The mutant was less responsive to exogenously supplied gibberellic acid than the wild-type, and profiling the transcription of genes involved in gibberellin synthesis and response revealed that a lesion in the mutant affected gibberellin signal transduction. The dnl3 phenotype was inherited as a single-dominant gene, mapping within a 19.1-kb region of chromosome 12, which was found to harbor three open reading frames. Resequencing the open reading frames revealed that the mutant carried an allele at one of the three genes that differed from the wild-type sequence by 2-bp deletions; this gene encoded a cellulose synthase-like D4 (CSLD4) protein. Therefore, OsCSLD4 is a candidate gene for DNL3. DNL3 was expressed in all of the rice organs tested at the heading stage, particularly in the leaves, roots, and culms. These results suggest that DNL3 plays important roles in rice leaf morphogenesis and vegetative development.
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Affiliation(s)
- L Shi
- Southern Regional Collaborative Innovation Center for Grain and Oil Crops, Hunan Agriculture University, Changsha, China.,Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - X J Wei
- Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - Y M N Adedze
- Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - Z H Sheng
- Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - S Q Tang
- Southern Regional Collaborative Innovation Center for Grain and Oil Crops, Hunan Agriculture University, Changsha, China.,Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - P S Hu
- Southern Regional Collaborative Innovation Center for Grain and Oil Crops, Hunan Agriculture University, Changsha, China.,Chinese National Center for Rice Improvement, State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - J L Wang
- Southern Regional Collaborative Innovation Center for Grain and Oil Crops, Hunan Agriculture University, Changsha, China
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6
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Affiliation(s)
- Lin-Tao Cai
- Center for Nanomedicine and Nanobiotechnology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Zong-Hai Sheng
- Center for Nanomedicine and Nanobiotechnology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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7
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Hu DH, Sheng ZH, Zhang PF, Yang DZ, Liu SH, Gong P, Gao DY, Fang ST, Ma YF, Cai LT. Hybrid gold-gadolinium nanoclusters for tumor-targeted NIRF/CT/MRI triple-modal imaging in vivo. Nanoscale 2013; 5:1624-1628. [PMID: 23334397 DOI: 10.1039/c2nr33543c] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, we prepared hybrid gold-gadolinium nanoclusters (NCs), which are ultrasmall, stable, biocompatible, and suitable for triple-modal NIRF/CT/MRI imaging. Upon intravenously injected, the hybrid NCs are effectively accumulated in tumor tissues and quickly clear by renal excretion, indicating their capacity of tumor targeting and low body residues. Notably, the ultrasmall hybrid NCs would penetrate into the solid tumor for capturing its heterostructure and do not induce potential toxicity in vivo. Hence, the well-defined hybrid gold-gadolinium NCs provide a versatile nanoprobe for cancer targeted imaging and diagnosis in vivo.
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Affiliation(s)
- De-Hong Hu
- Guangdong Key Laboratory of Nanomedicine, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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8
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Su Q, Mochida S, Tian JH, Mehta R, Sheng ZH. SNAP-29: a general SNARE protein that inhibits SNARE disassembly and is implicated in synaptic transmission. Proc Natl Acad Sci U S A 2001; 98:14038-43. [PMID: 11707603 PMCID: PMC61163 DOI: 10.1073/pnas.251532398] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Using the yeast two-hybrid system with syntaxin-1A as bait, we isolated soluble NSF attachment protein (SNAP)-29 from a human brain cDNA library. Synaptosomal fractionation and immunocytochemical staining of hippocampal neurons in culture showed that SNAP-29 is present at synapses and is predominantly associated with synaptic vesicles. The interaction of SNAP-29 with syntaxin-1 was further confirmed with immunoprecipitation analysis. Binding competition studies with SNAP-29 demonstrated that it could compete with alpha-SNAP for binding to synaptic SNAP receptors (SNAREs) and consequently inhibit disassembly of the SNARE complex. Introduction of SNAP-29 into presynaptic superior cervical ganglion neurons in culture significantly inhibited synaptic transmission in an activity-dependent manner. Although SNAP-29 has been suggested to be a general SNARE component in membrane trafficking, our findings suggest that it may function as a regulator of SNARE complex disassembly and modulate the process of postfusion recycling of the SNARE components.
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Affiliation(s)
- Q Su
- Synaptic Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-4154, USA
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9
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Abstract
cAMP-dependent protein kinase A (PKA) can modulate synaptic transmission by acting directly on unknown targets in the neurotransmitter secretory machinery. Here we identify Snapin, a protein of relative molecular mass 15,000 that is implicated in neurotransmission by binding to SNAP-25, as a possible target. Deletion mutation and site-directed mutagenetic experiments pinpoint the phosphorylation site to serine 50. PKA-phosphorylation of Snapin significantly increases its binding to synaptosomal-associated protein-25 (SNAP-25). Mutation of Snapin serine 50 to aspartic acid (S50D) mimics this effect of PKA phosphorylation and enhances the association of synaptotagmin with the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex. Furthermore, treatment of rat hippocampal slices with nonhydrolysable cAMP analogue induces in vivo phosphorylation of Snapin and enhances the interaction of both Snapin and synaptotagmin with the SNARE complex. In adrenal chromaffin cells, overexpression of the Snapin S50D mutant leads to an increase in the number of release-competent vesicles. Our results indicate that Snapin may be a PKA target for modulating transmitter release through the cAMP-dependent signal-transduction pathway.
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Affiliation(s)
- M G Chheda
- Synaptic Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 36 Convent Drive, Bethesda, Maryland 20892-4154, USA
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10
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Tang ZG, Xu XP, Sheng ZH, Liu SF. The role of cellular trace elements in oral carcinogenesis induced by 4-nitroquinoline 1-oxide(4NQO). Hunan Yi Ke Da Xue Xue Bao 2000; 25:323-6. [PMID: 12205989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
The aim of this study was to define the changes of cellular trace element concentration during the carcinogenesis process of Wistar rat palatine mucosa squamous epithelial cell induced by 4-nitroquinoline-1-oxide (4NQO). 4NQO was painted three times weekly for nineteen weeks on the palatine mucosae of 28 Wistar rats. Histologically normal, precancerous and squamous epithelial cell carcinoma tissues were obtained, and were studied by electron probe X-ray microanalysis. The measured elements were copper (Cu), zinc (Zn), selenium (Se), and molybdenum (Mo). The results were that both copper and zinc in the cellular nucleus and cytoplasm of the squamous epithelial carcinoma cells were significantly decreased. The concentration of cytoplasmic molybdenum significantly decreased in precancerous cells and significantly increased in squamous epithelial carcinoma cells. Minor changes in the concentration of selenium were observed in the process of normal to precancerous and then to cancerous cells. Cu/Zn increased in squamous epithelial carcinoma cells and Cu/Se and Zn/Se decreased in squamous epithelial carcinoma cells. These results suggest that the changes in intracellular copper, zinc, molybdenum are distinctly related to experimental oral carcinogenesis.
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Affiliation(s)
- Z G Tang
- Department of Oral and Maxillofacial Surgery, Xiangya Hospital, Hunan Medical University, Changsha 410008
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11
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Abstract
Syntaxin-1 is a key component of the synaptic vesicle docking/fusion machinery that forms the SNARE complex with VAMP/synaptobrevin and SNAP-25. Identifying proteins that modulate SNARE complex formation is critical for understanding the molecular mechanisms underlying neurotransmitter release and its modulation. We have cloned and characterized a protein called syntaphilin that is selectively expressed in brain. Syntaphilin competes with SNAP-25 for binding to syntaxin-1 and inhibits SNARE complex formation by absorbing free syntaxin-1. Transient overexpression of syntaphilin in cultured hippocampal neurons significantly reduces neurotransmitter release. Furthermore, introduction of syntaphilin into presynaptic superior cervical ganglion neurons in culture inhibits synaptic transmission. These findings suggest that syntaphilin may function as a molecular clamp that controls free syntaxin-1 availability for the assembly of the SNARE complex, and thereby regulates synaptic vesicle exocytosis.
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Affiliation(s)
- G Lao
- Synaptic Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-4154, USA
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12
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Pozzo-Miller LD, Gottschalk W, Zhang L, McDermott K, Du J, Gopalakrishnan R, Oho C, Sheng ZH, Lu B. Impairments in high-frequency transmission, synaptic vesicle docking, and synaptic protein distribution in the hippocampus of BDNF knockout mice. J Neurosci 1999; 19:4972-83. [PMID: 10366630 PMCID: PMC6782660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/1999] [Revised: 03/16/1999] [Accepted: 04/05/1999] [Indexed: 02/12/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) promotes long-term potentiation (LTP) at hippocampal CA1 synapses by a presynaptic enhancement of synaptic transmission during high-frequency stimulation (HFS). Here we have investigated the mechanisms of BDNF action using two lines of BDNF knockout mice. Among other presynaptic impairments, the mutant mice exhibited more pronounced synaptic fatigue at CA1 synapses during high-frequency stimulation, compared with wild-type animals. Quantitative analysis of CA1 synapses revealed a significant reduction in the number of vesicles docked at presynaptic active zones in the mutant mice. Synaptosomes prepared from the mutant hippocampus exhibited a marked decrease in the levels of synaptophysin as well as synaptobrevin [vesicle-associated membrane protein (VAMP-2)], a protein known to be involved in vesicle docking and fusion. Treatment of the mutant slices with BDNF reversed the electrophysiological and biochemical deficits in the hippocampal synapses. Taken together, these results suggest a novel role for BDNF in the mobilization and/or docking of synaptic vesicles to presynaptic active zones.
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Affiliation(s)
- L D Pozzo-Miller
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke (NINDS), National Institutes of Health, Bethesda, Maryland 20892, USA
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13
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Abstract
Synaptic vesicle docking and fusion are mediated by the assembly of a stable SNARE core complex of proteins, which include the synaptic vesicle membrane protein VAMP/synaptobrevin and the plasmalemmal proteins syntaxin and SNAP-25. We have now identified another SNAP-25-binding protein, called Snapin. Snapin was enriched in neurons and exclusively located on synaptic vesicle membranes. It associated with the SNARE complex through direct interaction with SNAP-25. Binding of recombinant Snapin-CT to SNAP-25 blocked the association of the SNARE complex with synaptotagmin. Introduction of Snapin-CT and peptides containing the SNAP-25 binding sequence into presynaptic superior cervical ganglion neurons in culture reversibly inhibited synaptic transmission. These results suggest that Snapin is an important component of the neurotransmitter release process through its modulation of the sequential interactions between the SNAREs and synaptotagmin.
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Affiliation(s)
- J M Ilardi
- Synaptic Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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14
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Sheng ZH, Westenbroek RE, Catterall WA. Physical link and functional coupling of presynaptic calcium channels and the synaptic vesicle docking/fusion machinery. J Bioenerg Biomembr 1998; 30:335-45. [PMID: 9758330 DOI: 10.1023/a:1021985521748] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
N- and P/Q-type calcium channels are localized in high density in presynaptic nerve terminals and are crucial elements in neuronal excitation-secretion coupling. In addition to mediating Ca2+ entry to initiate transmitter release, they are thought to interact directly with proteins of the synaptic vesicle docking/fusion machinery. As outlined in the preceding article, these calcium channels can be purified from brain as a complex with SNARE proteins which are involved in exocytosis. In addition, N-type and P/Q-type calcium channels are co-localized with syntaxin in high-density clusters in nerve terminals. Here we review the role of the synaptic protein interaction (synprint) sites in the intracellular loop II-III (L(II-III)) of both alpha1B and alpha1A subunits of N-type and P/Q-type calcium channels, which bind to syntaxin, SNAP-25, and synaptotagmin. Calcium has a biphasic effect on the interactions of N-type calcium channels with SNARE complexes, stimulating optimal binding in the range of 10-20 microM. PKC or CaM KII phosphorylation of the N-type synprint peptide inhibits interactions with native brain SNARE complexes containing syntaxin and SNAP-25. Introduction of the synprint peptides into presynaptic superior cervical ganglion neurons reversibly inhibits EPSPs from synchronous transmitter release by 42%. At physiological Ca2+ concentrations, synprint peptides cause an approximate 25% reduction in transmitter release of injected frog neuromuscular junction in cultures, consistent with detachment of 70% of the docked vesicles from calcium channels based on a theoretical model. Together, these studies suggest that presynaptic calcium channels not only provide the calcium signal required by the exocytotic machinery, but also contain structural elements that are integral to vesicle docking, priming, and fusion processes.
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Affiliation(s)
- Z H Sheng
- Synaptic Function Unit, NINDS, NIH, Bethesda, MD 20892, USA
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15
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Yokoyama CT, Sheng ZH, Catterall WA. Phosphorylation of the synaptic protein interaction site on N-type calcium channels inhibits interactions with SNARE proteins. J Neurosci 1997; 17:6929-38. [PMID: 9278528 PMCID: PMC6573282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The synaptic protein interaction (synprint) site on the N-type calcium channel alpha1B subunit binds to the soluble N-ethylmaleimide-sensitive attachment factor receptor (SNARE) proteins syntaxin and synaptosomal protein of 25 kDa (SNAP-25), and this association may be required for efficient fast synaptic transmission. Protein kinase C (PKC) and calcium and calmodulin-dependent protein kinase type II (CaM KII) phosphorylated a recombinant his-tagged synprint site polypeptide rapidly to a stoichiometry of 3-4 mol of phosphate/mol, whereas cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG) phosphorylated the synprint peptide more slowly to a stoichiometry of <1 mol/mol. Two-dimensional phosphopeptide mapping revealed similar patterns of phosphorylation of synprint polypeptides and native rat brain N-type calcium channel alpha1B subunits by PKC and Cam KII. Phosphorylation of the synprint peptide with PKC or CaM KII, but not PKA or PKG, strongly inhibited binding of recombinant syntaxin or SNAP-25, even at a level of free calcium (15 microM) that stimulates maximal binding. In contrast, phosphorylation of syntaxin and SNAP-25 with PKC and CaM KII did not affect interactions with the synprint site. Binding assays with polypeptides representing the N- and C-terminal halves of the synprint site indicate that the PKC- and CaM KII-mediated inhibition of binding involves multiple, disperse phosphorylation sites. PKC or CaM KII phosphorylation of the synprint peptide also inhibited its interactions with native rat brain SNARE complexes containing syntaxin and SNAP-25. These results suggest that phosphorylation of the synprint site by PKC or CaM KII may serve as a biochemical switch for interactions between N-type calcium channels and SNARE protein complexes.
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Affiliation(s)
- C T Yokoyama
- Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, Washington 98195, USA
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16
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Rettig J, Heinemann C, Ashery U, Sheng ZH, Yokoyama CT, Catterall WA, Neher E. Alteration of Ca2+ dependence of neurotransmitter release by disruption of Ca2+ channel/syntaxin interaction. J Neurosci 1997; 17:6647-56. [PMID: 9254677 PMCID: PMC6573125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Presynaptic N-type calcium channels interact with syntaxin and synaptosome-associated protein of 25 kDa (SNAP-25) through a binding site in the intracellular loop connecting domains II and III of the alpha1 subunit. This binding region was loaded into embryonic spinal neurons of Xenopus by early blastomere injection. After culturing, synaptic transmission of peptide-loaded and control cells was compared by measuring postsynaptic responses under different external Ca2+ concentrations. The relative transmitter release of injected neurons was reduced by approximately 25% at physiological Ca2+ concentration, whereas injection of the corresponding region of the L-type Ca2+ channel had virtually no effect. When applied to a theoretical model, these results imply that 70% of the formerly linked vesicles have been uncoupled after action of the peptide. Our data suggest that severing the physical interaction between presynaptic calcium channels and synaptic proteins will not prevent synaptic transmission at this synapse but will make it less efficient by shifting its Ca2+ dependence to higher values.
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Affiliation(s)
- J Rettig
- Department of Membrane Biophysics, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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17
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Sheng ZH, Yokoyama CT, Catterall WA. Interaction of the synprint site of N-type Ca2+ channels with the C2B domain of synaptotagmin I. Proc Natl Acad Sci U S A 1997; 94:5405-10. [PMID: 9144250 PMCID: PMC24691 DOI: 10.1073/pnas.94.10.5405] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
N-type Ca2+ channels mediate Ca2+ influx, which initiates fast exocytosis of neurotransmitters at synapses, and they interact directly with the SNARE proteins syntaxin and SNAP-25 (synaptosome-associated protein of 25 kDa) through a synaptic protein interaction (synprint) site in the intracellular loop connecting domains II and III of their alpha1B subunits. Introduction of peptides containing the synprint site into presynaptic neurons reversibly inhibits synaptic transmission, confirming the importance of interactions with this site in synaptic transmission. Here we report a direct interaction of the synprint peptide from N-type Ca2+ channels with synaptotagmin I, an important Ca2+ sensor for exocytosis, as measured by an affinity-chromatography binding assay and a solid-phase immunoassay. This interaction is mediated by the second C2 domain (C2B) of synaptotagmin I, but is not regulated by Ca2+. Using both immobilized recombinant proteins and native presynaptic membrane proteins, we found that the synprint peptide and synaptotagmin competitively interact with syntaxin. This interaction is Ca2+-dependent because of the Ca2+ dependence of the interactions between syntaxin and these two proteins. These results provide a molecular basis for a physical link between Ca2+ channels and synaptotagmin, and suggest that N-type Ca2+ channels may undergo a complex series of Ca2+-dependent interactions with multiple presynaptic proteins during neurotransmission.
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Affiliation(s)
- Z H Sheng
- Department of Pharmacology, Box 357280, University of Washington, Seattle, WA 98195-7280, USA
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Mochida S, Sheng ZH, Baker C, Kobayashi H, Catterall WA. Inhibition of neurotransmission by peptides containing the synaptic protein interaction site of N-type Ca2+ channels. Neuron 1996; 17:781-8. [PMID: 8893034 DOI: 10.1016/s0896-6273(00)80209-3] [Citation(s) in RCA: 237] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
N-type Ca2+ channels bind directly to the synaptic core complex of VAMP/synaptobrevin, syntaxin, and SNAP-25. Peptides containing the synaptic protein interaction ("synprint") site caused dissociation of N-type Ca2+ channels from the synaptic core complex. Introduction of synprint peptides into presynaptic superior cervical ganglion neurons reversibly inhibited synaptic transmission. Fast EPSPs due to synchronous transmitter release were inhibited, while late EPSPs arising from asynchronous release following a train of action potentials were increased and paired-pulse facilitation was increased. The corresponding peptides from L-type Ca2+ channels had no effect, and the N-type peptides had no effect on Ca2+ currents through N-type Ca2+ channels. These results are consistent with the hypothesis that binding of the synaptic core complex to presynaptic N-type Ca2+ channels is required for Ca2+ influx to elicit rapid, synchronous neurotransmitter release.
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Affiliation(s)
- S Mochida
- Department of Physiology, Tokyo Medical College, Japan
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Rettig J, Sheng ZH, Kim DK, Hodson CD, Snutch TP, Catterall WA. Isoform-specific interaction of the alpha1A subunits of brain Ca2+ channels with the presynaptic proteins syntaxin and SNAP-25. Proc Natl Acad Sci U S A 1996; 93:7363-8. [PMID: 8692999 PMCID: PMC38990 DOI: 10.1073/pnas.93.14.7363] [Citation(s) in RCA: 256] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Presynaptic Ca2+ channels are crucial elements in neuronal excitation-secretion coupling. In addition to mediating Ca2+ entry to initiate transmitter release, they are thought to interact directly with proteins of the synaptic vesicle docking/fusion machinery. Here we report isoform-specific, stoichiometric interaction of the BI and rbA isoforms of the alpha1A subunit of P/Q-type Ca2+ channels with the presynaptic membrane proteins syntaxin and SNAP-25 in vitro and in rat brain membranes. The BI isoform binds to both proteins, while only interaction with SNAP-25 can be detected in vitro for the rbA isoform. The synaptic protein interaction ("synprint") site involves two adjacent segments of the intracellular loop connecting domains II and III between amino acid residues 722 and 1036 of the BI sequence. This interaction is competitively blocked by the corresponding region of the N-type Ca2+ channel, indicating that these two channels bind to overlapping regions of syntaxin and SNAP-25. Our results provide a molecular basis for a physical link between Ca2+ influx into nerve terminals and subsequent exocytosis of neurotransmitters at synapses that have presynaptic Ca2+ channels containing alpha1A subunits.
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Affiliation(s)
- J Rettig
- Department of Pharmacology, University of Washington, Seattle 98195-7280, USA
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Abstract
Neurotransmitter release is initiated by influx of Ca2+ through voltage-gated Ca2+ channels, within 200 microseconds of the action potential arriving at the synaptic terminal, as the Ca2+ concentration increases from 100 nM to > 200 microM. Exocytosis requires high Ca2+ concentration, with a threshold of 20-50 microM and half-maximal activation at 190 microM. The synaptic membrane proteins syntaxin, 25K synaptosome-associated protein (SNAP25), and vesicle-associated membrane protein (VAMP)/synaptobrevin, are thought to form a synaptic core complex which mediates vesicle docking and membrane fusion. Synaptotagmin may be the low-affinity Ca(2+)-sensor, but other Ca(2+)-sensors are involved as residual neurotransmission persists in synaptotagmin-null mutants. Syntaxin binds to N-type Ca2+ channels at a site in the intracellular loop connecting domains II and III. Here we describe Ca(2+)-dependent interaction of this site with syntaxin and SNAP25 which has a biphasic dependence on Ca2+, with maximal binding at 20 microM free Ca2+, near the threshold for transmitter release. Ca(2+)-dependent interaction of Ca2+ channels with the synaptic core complex may be important for Ca(2+)-dependent docking and fusion of synaptic vesicles.
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Affiliation(s)
- Z H Sheng
- Department of Pharmacology, University of Washington, Seattle 98195-7280, USA
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21
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Abstract
Immunochemical studies have suggested a tight association of syntaxin with N-type calcium channels. Syntaxin specifically interacts with the fusion proteins containing the cytoplasmic loop (LII-III) between homologous repeats II and III of the alpha 1 subunit of the class B N-type calcium channel (alpha 1B) from rat brain, but not with those of the class A Q-type (alpha 1A) or the class S L-type (alpha 1S) calcium channels. This interaction is mediated by an 87 amino acid sequence (773-859) containing two overlapping predicted helix-loop-helix domains. The 87 amino acid peptide can specifically block binding of native N-type calcium channels to syntaxin, indicating that this binding site is required for stable interaction of these two proteins. Interaction takes place with the C-terminal one-third of syntaxin (residues 181-288), which is thought to be anchored in the presynaptic plasma membrane. Our results suggest a direct interaction between the cytoplasmic domains of these two presynaptic membrane proteins that could have an important role in the targeting and docking of synaptic vesicles near N-type calcium channels, enabling tight structural and functional association of calcium entry sites and neurotransmitter release sites.
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Affiliation(s)
- Z H Sheng
- Department of Pharmacology, University of Washington, Seattle 98195
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Sheng ZH, Zhang H, Barchi RL, Kallen RG. Molecular cloning and functional analysis of the promoter of rat skeletal muscle voltage-sensitive sodium channel subtype 2 (rSkM2): evidence for muscle-specific nuclear protein binding to the core promoter. DNA Cell Biol 1994; 13:9-23. [PMID: 8286044 DOI: 10.1089/dna.1994.13.9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
rSkM2 is a tetrodotoxin-resistant rat skeletal muscle voltage-sensitive sodium channel that is expressed in immature and denervated skeletal muscle and in adult heart. We have isolated a 3.7-kb gene segment that contains the first exon, multiple transcription initiation sites, the core promoter (nt -102 to +1), GC-rich elements (Sp1 recognition sites), three overlapping C-rich motifs (important for muscle-specific expression of some muscle genes), and multiple CANNTG (E-box) motifs (MyoD binding sites). A deletion analysis of the 5' upstream 2.8-kb segment, driving the rSkM2 core promoter, has localized a muscle-restrictive enhancer element (MRSE) at least 2 kb upstream from the core promoter. The core promoter is silenced by an additional cis element (-645/-506). The positive and negative cis-elements together drive transcription of the chloramphenicol acetyltransferase (CAT) reporter gene from the core promoter at about the same level as does the core promoter alone in a skeletal muscle differentiation stage-specific manner. Gel-shift assays have identified sequence- and cell-type-specific proteins that bind to a 16-bp region (-44/-29) containing C-rich motifs. Muscle-specific complexes formed from muscle cell nuclear extracts and a 16-bp element (-44/-29) are competed by unlabeled -44/-29 oligonucleotide but not by several mutant oligonucleotides that implicate nucleotides -40 to -38 and -34 to -32 in the binding of a nuclear protein (designated SkM2 transcription factor 1, SkM2-TF1). We conclude that rSkM2 gene expression depends on the interactions of positive and negative transcriptional regulators with tissue- and developmental stage-specific core promoter elements.
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Affiliation(s)
- Z H Sheng
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia 19104-6059
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Kallen RG, Sheng ZH, Yang J, Chen LQ, Rogart RB, Barchi RL. Primary structure and expression of a sodium channel characteristic of denervated and immature rat skeletal muscle. Neuron 1990; 4:233-42. [PMID: 2155010 DOI: 10.1016/0896-6273(90)90098-z] [Citation(s) in RCA: 213] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The alpha subunit of a voltage-sensitive sodium channel characteristic of denervated rat skeletal muscle was cloned and characterized. The cDNA encodes a 2018 amino acid protein (SkM2) that is homologous to other recently cloned sodium channels, including a tetrodotoxin (TTX)-sensitive sodium channel from rat skeletal muscle (SkM1). The SkM2 protein is no more homologous to SkM1 than to the rat brain sodium channels and differs notably from SkM1 in having a longer cytoplasmic loop joining domains 1 and 2. Steady-state mRNA levels for SkM1 and SkM2 are regulated differently during development and following denervation: the SkM2 mRNA level is highest in early development, when TTX-insensitive channels predominate, but declines rapidly with age as SkM1 mRNA increases; SkM2 mRNA is not detectable in normally innervated adult skeletal muscle but increases greater than 100-fold after denervation; rat cardiac muscle has abundant SkM2 mRNA but no detectable SkM1 message. These findings suggest that SkM2 is a TTX-insensitive sodium channel expressed in both skeletal and cardiac muscle.
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Affiliation(s)
- R G Kallen
- David Mahoney Institute of Neurological Sciences, University of Pennsylvania School of Medicine, Philadelphia 19104
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Trimmer JS, Cooperman SS, Tomiko SA, Zhou JY, Crean SM, Boyle MB, Kallen RG, Sheng ZH, Barchi RL, Sigworth FJ. Primary structure and functional expression of a mammalian skeletal muscle sodium channel. Neuron 1989; 3:33-49. [PMID: 2559760 DOI: 10.1016/0896-6273(89)90113-x] [Citation(s) in RCA: 451] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We describe the isolation and characterization of a cDNA encoding the alpha subunit of a new voltage-sensitive sodium channel, microI, from rat skeletal muscle. The 1840 amino acid microI peptide is homologous to alpha subunits from rat brain, but, like the protein from eel electroplax, lacks an extended (approximately 200) amino acid segment between homologous domains I and II. Northern blot analysis indicates that the 8.5 kb microI transcript is preferentially expressed in skeletal muscle. Sodium channels expressed in Xenopus oocytes from synthetic RNA encoding microI are blocked by tetrodotoxin and mu-conotoxin at concentrations near 5 nM. The expressed sodium channels have gating kinetics similar to the native channels in rat muscle fibers, except that inactivation occurs more slowly.
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Affiliation(s)
- J S Trimmer
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
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