By means of the two-compartment system. PTL-channels, the first lectin channels formed on planar lipid bilayers by Pinellia ternata lectin (PTL) have been studied. The results show (i) PTL-channels are voltage-indepen...By means of the two-compartment system. PTL-channels, the first lectin channels formed on planar lipid bilayers by Pinellia ternata lectin (PTL) have been studied. The results show (i) PTL-channels are voltage-independent and have apparent subunits; (ii) in 50 mmol/L KC1 and 25 mmol/L BaCl2 solutions, a single channel has unit conductance of 21 pS and 42 pS, respectively; (iii) the channel exhibits a slightly higher permeability to divalent than monovalent cation (PBa/PK=4.1), and (iv) the selectivity among divalent or monovalent cations is poor. The cation selectivity sequence for the channel will follow PBa(7. 0)-Psr (6. 4)~PMg(6. 4)>PK(1. 7)>PN.(1. 0)~PLi(l. 0).Moreover, these data also give explanation to the facilitatory action of PTL on the release of acetyl-choline from motor nerve terminals.展开更多
Pinellia ternata lectin (PTL) extracted from the fresh juice of rhizome of pinellia ternata used as a traditional Chinese medicine facilitated the quantal release of acetylcholine (ACh) in the mouse motor nerve termin...Pinellia ternata lectin (PTL) extracted from the fresh juice of rhizome of pinellia ternata used as a traditional Chinese medicine facilitated the quantal release of acetylcholine (ACh) in the mouse motor nerve terminals and formed cation channels in artificial lipid bilayer. Here we report the action of PTL on presynaptic membrane currents of motor nerve terminals.The experiments were performed on the intercostal nerve triangularis sterni muscle preparations. By means of the perineurial recording, the effects of PTL on the sodium current in the preterminal part , three potassium currents and two calcium currents generated from the nerve terminals were investigated. The results show that PTL increases voltage-dependent fast Ca2+ current (ICa,f), Na+ current (INa) and Ca2+-acti-vated K+ current (IK,Ca) without action on either the voltage-dependent fast K+ current (IK,f) or the slow K+ current (IK,S). These effects are irreversible, but can be reversed by mannan, the specific binding sugar for PTL.The total action of PTL can be considered to raise [Ca2+], by promoting Ca2+ influx, and then facilitate the neurotransmitter release. To our knowledge, this is the first report about the influence of lectin on presynaptic membrane currents at mammalian motor nerve terminals.展开更多
In this paper, Pinellia ternata lectin (PTL) purified from 95% saturated ammonium sulfate precipitation by applying mannose-Sepharose 4B affinity column chromatography was first described. The mannose-Sepharose 4B aff...In this paper, Pinellia ternata lectin (PTL) purified from 95% saturated ammonium sulfate precipitation by applying mannose-Sepharose 4B affinity column chromatography was first described. The mannose-Sepharose 4B affinity adsorption gel has already been designed and prepared before the experiments according the combinative characterization between lectin and mannose. Mass spectrometry analysis result shows that PTL is a glycoprotein with the molecular weight of 12.165 kD. It was conclude that PTL had strong agglutination effects on mouse red blood cells, and the minimum reaction concentration was 25 μg/ml according the Hemagglutination. Results of automatic amino acid analysis indicated that PTL mainly contained 15 varieties of amino acids, of which the minimum content was cysteine and aspartate was the maximum. Cell experiment results suggested that PTL of low concentrations (0.004 mg/ml, 0.02 mg/ml and 0.1 mg/ml) promoted HeLa cell proliferation, but the effect weakened with the concentrations and treated-time increasing. However, the HeLa cells pro- liferation was intensively inhibited by higher PTL concentrations (0.5 mg/ml and 1 mg/ml), and the effect increased in a dose and time dependent manner.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘By means of the two-compartment system. PTL-channels, the first lectin channels formed on planar lipid bilayers by Pinellia ternata lectin (PTL) have been studied. The results show (i) PTL-channels are voltage-independent and have apparent subunits; (ii) in 50 mmol/L KC1 and 25 mmol/L BaCl2 solutions, a single channel has unit conductance of 21 pS and 42 pS, respectively; (iii) the channel exhibits a slightly higher permeability to divalent than monovalent cation (PBa/PK=4.1), and (iv) the selectivity among divalent or monovalent cations is poor. The cation selectivity sequence for the channel will follow PBa(7. 0)-Psr (6. 4)~PMg(6. 4)>PK(1. 7)>PN.(1. 0)~PLi(l. 0).Moreover, these data also give explanation to the facilitatory action of PTL on the release of acetyl-choline from motor nerve terminals.
基金Project supported by the National Natural Science Foundation of China.
文摘Pinellia ternata lectin (PTL) extracted from the fresh juice of rhizome of pinellia ternata used as a traditional Chinese medicine facilitated the quantal release of acetylcholine (ACh) in the mouse motor nerve terminals and formed cation channels in artificial lipid bilayer. Here we report the action of PTL on presynaptic membrane currents of motor nerve terminals.The experiments were performed on the intercostal nerve triangularis sterni muscle preparations. By means of the perineurial recording, the effects of PTL on the sodium current in the preterminal part , three potassium currents and two calcium currents generated from the nerve terminals were investigated. The results show that PTL increases voltage-dependent fast Ca2+ current (ICa,f), Na+ current (INa) and Ca2+-acti-vated K+ current (IK,Ca) without action on either the voltage-dependent fast K+ current (IK,f) or the slow K+ current (IK,S). These effects are irreversible, but can be reversed by mannan, the specific binding sugar for PTL.The total action of PTL can be considered to raise [Ca2+], by promoting Ca2+ influx, and then facilitate the neurotransmitter release. To our knowledge, this is the first report about the influence of lectin on presynaptic membrane currents at mammalian motor nerve terminals.
文摘In this paper, Pinellia ternata lectin (PTL) purified from 95% saturated ammonium sulfate precipitation by applying mannose-Sepharose 4B affinity column chromatography was first described. The mannose-Sepharose 4B affinity adsorption gel has already been designed and prepared before the experiments according the combinative characterization between lectin and mannose. Mass spectrometry analysis result shows that PTL is a glycoprotein with the molecular weight of 12.165 kD. It was conclude that PTL had strong agglutination effects on mouse red blood cells, and the minimum reaction concentration was 25 μg/ml according the Hemagglutination. Results of automatic amino acid analysis indicated that PTL mainly contained 15 varieties of amino acids, of which the minimum content was cysteine and aspartate was the maximum. Cell experiment results suggested that PTL of low concentrations (0.004 mg/ml, 0.02 mg/ml and 0.1 mg/ml) promoted HeLa cell proliferation, but the effect weakened with the concentrations and treated-time increasing. However, the HeLa cells pro- liferation was intensively inhibited by higher PTL concentrations (0.5 mg/ml and 1 mg/ml), and the effect increased in a dose and time dependent manner.
