Bönigk W, Bradley J, Müller F, Sesti F, Boekhoff I, Ronnett G V, Kaupp U B, Frings S
Forschungszentrum Jülich, Institut für Biologische Informationsverarbeitung, 52425 Jülich, Germany.
J Neurosci. 1999 Jul 1;19(13):5332-47. doi: 10.1523/JNEUROSCI.19-13-05332.1999.
Cyclic nucleotide-gated (CNG) channels play central roles in visual and olfactory signal transduction. In the retina, rod photoreceptors express the subunits CNCalpha1 and CNCbeta1a. In cone photoreceptors, only CNCalpha2 expression has been demonstrated so far. Rat olfactory sensory neurons (OSNs) express two homologous subunits, here designated CNCalpha3 and CNCalpha4. This paper describes the characterization of CNCbeta1b, a third subunit expressed in OSNs and establishes it as a component of the native channel. CNCbeta1b is an alternate splice form of the rod photoreceptor CNCbeta1a subunit. Analysis of mRNA and protein expression together suggest co-expression of all three subunits in sensory cilia of OSNs. From single-channel analyses of native rat olfactory channels and of channels expressed heterologously from all possible combinations of the CNCalpha3, -alpha4, and -beta1b subunits, we conclude that the native CNG channel in OSNs is composed of all three subunits. Thus, CNG channels in both rod photoreceptors and olfactory sensory neurons result from coassembly of specific alpha subunits with various forms of an alternatively spliced beta subunit.
环核苷酸门控（CNG）通道在视觉和嗅觉信号转导中发挥着核心作用。在视网膜中，视杆光感受器表达亚基CNCalpha1和CNCbeta1a。在视锥光感受器中，迄今为止仅证实有CNCalpha2表达。大鼠嗅觉感觉神经元（OSN）表达两种同源亚基，在此命名为CNCalpha3和CNCalpha4。本文描述了在OSN中表达的第三种亚基CNCbeta1b的特性，并确定它是天然通道的一个组成部分。CNCbeta1b是视杆光感受器CNCbeta1a亚基的一种可变剪接形式。对mRNA和蛋白质表达的分析共同表明，这三种亚基在OSN的感觉纤毛中共表达。通过对天然大鼠嗅觉通道以及从CNCalpha3、-alpha4和-beta1b亚基的所有可能组合中异源表达的通道进行单通道分析，我们得出结论，OSN中的天然CNG通道由所有这三种亚基组成。因此，视杆光感受器和嗅觉感觉神经元中的CNG通道都是由特定的α亚基与可变剪接的β亚基的各种形式共同组装而成的。
