The miniature viral K+ channel Kcv represents the pore module of all K+ channels. A synthetic gene of Kcv with an elevated GC content compared to that of the wild-type gene was expressed heterologously in Pichia pastoris, and the purified protein was functionally reconstituted into liposomes. Biochemical assays reveal a remarkable cation selctive stability of the channel tetramer via SDS-PAGE. Only cations, which permeate Kcv, were able to protect the oligomer against disassembly into monomers at high temperatures. Electrophysiological characterization of the single Kcv channel reveals a saturating conductance (Lambda(max)) of 360 pS; the single-channel current-voltage relation was strongly rectifying with a negative slope conductance at extreme voltages. The channel was highly selective for K+ and was blocked by Ba2+ and in a side specific manner by Na+ and Cs+ also. The channel conducted Rb+, but as a consequence, the channel was shifted into a hyperactive state. We conclude that specific binding interactions of cations in the conductive pathway are an important determinant of channel stability and function.
|Titolo:||Molecular properties of Kcv, a virus encoded K+ channel|
|Autori interni:||MORONI, ANNA (Penultimo)|
PAGLIUCA, CINZIA (Primo)
|Settore Scientifico Disciplinare:||Settore BIO/04 - Fisiologia Vegetale|
|Data di pubblicazione:||30-gen-2007|
|Digital Object Identifier (DOI):||10.1021/bi061530w|
|Appare nelle tipologie:||01 - Articolo su periodico|