A molecular dynamics simulation has been performed on a synthetic membrane-spanning ion channel, consisting of four α-helical peptides, each of which is composed of the sequence Ac-(LSLLLSL)3-CONH
2. In the present simulation, the channel was initially assembled dynamically as a parallel bundle in the octane portion of a phase separated water/octane system, which provided a membrane-mimetic environment, without imposing any structural constraints. After more than one nanosecond, the four helices were found to adopt an associated dimer state with two-fold symmetry, which after a further 3 ns evolved to a coiled-coil tetrameric structure with a left-handed twist. Based on the simulation, we proposed a phenomenological model to describe the two-states of the channel.