Multiple conductance classes of mouse nicotinic acetylcholine receptors expressed in Xenopus oocytes.

Abstract
Acetylcholine receptor (AcChoR) subunit mRNAs transcribed from mouse BC3H-1 cDNAs were injected into Xenopus oocytes and the expressed AcChoR channels were examined by single channel recording. Injection of .alpha.-, .beta.-, .gamma.-, and .delta.-subunit mRNAs produced two predominant channel classes with conductances of .apprxeq.50 and .apprxeq.12pS, while infrequent openings of .apprxeq.25-pS channels were also observed. Injection of .alpha.-, .beta.-, and .gamma.-subunit mRNAs produced a single class of .apprxeq.12-pS AcChoR channels, which resembled the smallest conductance channels present in .alpha..beta..gamma..delta.-injected oocytes. Assembly of .delta.-less channels may thus explain the lowest conductance AcChoR channels in .alpha..beta..gamma..delta.-injected oocytes and might also account for similar channels that have been observed in vertebrate skeletal muscle.