Is the mammalian porin channel, VDAC, a perfect cylinder in the high conductance state?
The mammalian porin channel (VDAC, porin-31BM) was reconstituted in planar lipid bilayers under voltage clamp conditions. The radii of both entrances of the channel were examined using a method that consisted in filling the channel with different non-electrolytes through its cis or trans entrances while recording single channel conductances. As a result it was found that the geometry of channels formed by porin-31BM could not be approximated by a perfectly cylindrical pore. In fact there is an asymmetry in the geometry of the channel: the diameters of the cis and trans entrances were estimated to be approximately 2 nm and approximately 4 nm respectively.
Carneiro
C M
CM
Center of Biological Sciences, Department of Biophysics and Radiobiology, Federal University of Pernambuco, Recife, PE, Brazil.
Krasilnikov
O V
OV
Yuldasheva
L N
LN
Campos de Carvalho
A C
AC
Nogueira
R A
RA
D000818:Animals; D002417:Cattle; D004553:Electric Conductivity; D004573:Electrolytes; D007473:Ion Channels / Q000737:chemistry / Q000502:physiology; D008051:Lipid Bilayers; D008322:Mammals; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology*; D008961:Models, Structural; D018482:Muscle, Skeletal / Q000502:physiology; D018408:Patch-Clamp Techniques; D011092:Polyethylene Glycols; D018272:Porins; D011487:Protein Conformation; D050994:Voltage-Dependent Anion Channels
D004573:Electrolytes; D007473:Ion Channels; D008051:Lipid Bilayers; D008565:Membrane Proteins; D018272:Porins; D050994:Voltage-Dependent Anion Channels; D011092:Polyethylene Glycols