Ion Permeability of Ciliary Membrane Vesicles Isolated from Tetrahymena. Single-Channel Recording Study on the Membrane Reconstituted into a Planar Lipid Bilayer

• Published in: Journal of biochemistry (Tokyo) 1986-12, Vol.100 (6), p.1569-1573
• Main Authors: KAWAHARA, Shigenori, KIRINO, Yutaka, NAGAO, Seiji, NOZAWA, Yoshinori
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Calcium - metabolism; Cell Membrane Permeability; Cell physiology; Cilia - metabolism; Electric Conductivity; Fundamental and applied biological sciences. Psychology; Ion Channels - drug effects; Ion Channels - metabolism; Lipid Bilayers - metabolism; Membrane and intracellular transports; Membrane Lipids - metabolism; Molecular and cellular biology; Tetrahymena - metabolism
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a121864

An ion channel in ciliary membrane vesicles isolated from Tetrahymena pyriformis NT-1 was characterized with a single-channel recording technique applied to the membrane reconstituted into a planar lipid bilayer made of soybean phospholipid. The gating of this channel is independent of membrane potential and it spends most of the time in its open-channel state. It is selective for metal cations over gluconate anion although it little distinguishes cations, Ca2+, Ba2+, Mg2+, and K+. This channel seems to be identical to the monovalent cation channel in Tetrahymena thermophila BIT cilia, which was recently reported by Oosawa and Sokabe {Am. J. Physiol. 249, C177–C179, 1985). The channel conductance saturates with increasing ion concentration. The maximum value (in pS) for the single-channel conductance obtained in symmetric solutions of sufficiently high concentration is in the order of K+(212)>Ba2+(41)>Ca2+(22)>Mg2+(20). On the other hand, the affinity of the channel for these ions is in the reverse order.