Exchange of conductance and gating properties between gap junction hemichannels.

Gap junction channels span the membranes of two adjacent cells and allow the gated transit of molecules as large as second messengers from cell to cell. The structure of the gap junction channel pore is not resolved. For identification of pore determinants we used a chimera of two connexins, cx46 and cx32E(1)43, that form membrane channels with distinct unit conductances and channel kinetics. Exchange of the first transmembrane segment (M1) between these connexins resulted in a chimera that exhibited most of the channel properties of the M1 donor, including single channel conductance, channel kinetics, and the preference to dwell at a subconductance level. The M1 segment thus appears to be an important determinant of conductance and gating properties of connexin channels.