A Stochastic Model of Voltage-Gating of Connexin-Based Gap Junction Channels Containing Fast and Slow Gates

Abstract

Connexins (Cxs), a family of membrane proteins, form gap junction (GJ) channels that provide a direct pathway for electrical and metabolic cell-cell interaction. Each hemichannel in the GJ channel contains fast and slow gates sensitive to transjunctional voltage (Vj). The fast gate operates between open and residual states with conductances of γF,o and γF,res, while the slow gate operates between open (γS,o) and fully closed (γS,closed=0) states; all γs rectify but at different degree. We developed a stochastic 16-state model (S16SM), which extends earlier reported S4SM (Paulauskas et al., 2009) and accounts operation of four gates in series, instead of two, to describe the gating properties of homotypic and heterotypic GJ channels.