Cation selectivity of channels formed at planar lipid bilayer by Pinellia ternata lectin[英]
By means of the two-compartment system, PTL-channels, the first lectin channels formed on planar lipid bilayers by Pinellia ternata lectin(PTL)have beenstudied. The results show(i)PTL-channels are voltage-independent and have apparent subunits; (ii)in 50 mmol/L KCl and 25 mmol/L BaCl_(2) 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(P_(Ba)/P_(k)=4.1), and (iv)the selectivity among divalent or monovalent cations is poor. The cation selectivity sequence for the channel will follow P_(Ba) (7.0)～P_(Sr)(6.4)～P_(Mg)(6.4)>P_(K)(1.7)>P_(Na)(1.0)～P_(Li)(1.0). Moreover, these data also give explanation to the facilitatory action of PTL on the release of acetylcholine from motor nerve terminals.