| The resulting dimer forms an ion channel in lipid membranes that is selective for monovalent cations only. |
| Recently, the recombinant protein was shown to be a dimer both in solution and in crystals. |
| We find that the tetramer and the dimer become less stable than the monomer as the pH is lowered. |
| The dimer, which maintains catalytic activity, was used throughout our studies. |
| At 50 mM reductant, some disulfide formation remains as revealed by the persistent dimer band. |
| The side chains of the substituted residues easily accommodate in the dimer interlace. |
