Reconstitution of channels from preparations enriched in lens gap junction protein MP70.
Detergent-solubilized ovine lens membrane proteins, enriched in the 70-kDa gap junction component (MP70), were reconstituted into planar lipid bilayers and analyzed for channel activities. Three distinct activities were found. Those showing conductance steps of 290 pS (symmetrical 150-mM KCl solutions) had properties similar to those reported earlier for MIP26 (Ehring, G.R., Zampighi, G., Horwitz, J., Bok, D., Hall, J.E. 1990. J. Gen. Physiol. 96:631-664.) of which minor amounts were normally present in the detergent-solubilized preparations. Two novel channel activities had unitary conductances of 90 and 45 pS, were halothane sensitive and did not discriminate between sodium and potassium ions. The 90-pS channel was asymmetrically voltage dependent, and its properties would be consistent with the expected properties of junctional hemichannels.
D000818:Animals; D017630:Connexins; D004553:Electric Conductivity; D005136:Eye Proteins / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D007473:Ion Channels / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D008051:Lipid Bilayers / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000032:analysis / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012756:Sheep; D012964:Sodium / Q000378:metabolism; D000099264:Connexin 50
D017630:Connexins; D005136:Eye Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D008562:Membrane Glycoproteins; D011188:Potassium; D012964:Sodium; D000099264:Connexin 50