Purified Lens Junctional Protein Forms Channels in Planar Lipid Films

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 82; no. 24; pp. 8468 - 8472
• Main Authors: Zampighi, Guido A., Hall, James E., Kreman, Michael
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01-12-1985; National Acad Sciences
• Subjects: Animals; Aquaporins; Cattle; Cell membranes; Detergents; Electric Conductivity; Electric current; Electric potential; Eye Proteins - isolation & purification; Eye Proteins - physiology; Freeze Fracturing; Gap junctions; Gels; Intercellular Junctions; Ion Channels; Lipid Bilayers; Lipids; Liposomes; Membrane Glycoproteins; Membrane Potentials; Molecular Weight; Octanols
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.82.24.8468

Junctions isolated from bovine lenses were solubilized with the detergent octyl glucoside, and their protein(s) was reconstituted in unilamellar vesicles. The protein(s) appears as annular-shaped intramembrane particles ≈ 10 nm in diameter on the vesicles' fracture faces. The addition of the vesicle-containing junctional protein(s) to both sides of preformed lipid films induced voltage-dependent channels. The channels have a conductance of 200 pS in 0.1 M salt solutions and are thus large enough to account for the electrical coupling observed between intact lens fibers; they turn off when the magnitude of the voltage is increased and in the presence of octanol. Although the identity of the reconstituted channels as the communicating pathway between lens fibers remains to be proven, it is most likely that the reconstituted channels are formed by MIP-26, the major protein component of the isolated lens junctions.