Isolation and purification of human blood plasma proteins able to form potassium channels in artificial bilayer lipid membrane
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- Venediktova, N.I., Kuznetsov, K.V., Gritsenko, E.N. et al. BIOPHYSICS (2012) 57: 621. doi:10.1134/S0006350912050259
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A protein fraction able to induce K+-selective transport across a bilayer lipid membrane was isolated from human blood plasma with the use of the detergent- and proteolytic enzyme-free method developed in our laboratory. After addition of the studied sample to the artificial membrane in the presence of 100 mM KCl, a discrete current change was observed. No channel activity was recorded in the presence of calcium and sodium ions. Channel-forming activity of the fraction was observed only in the presence of K+. Using a threefold gradient of KCl in the presence of studied proteins, a potassium-selective potential balanced by voltage of −29 mV was registered. This value is very close to the theoretical Nernst potential in this case. This means that the examined ion channel is cation-selective. According to the data obtained with MS-MALDI-TOF/TOF and NCBI database, three protein components were identified in the isolated sample.