Solute transport.
<P>
<BR><LI> Cations  (such  as potassium ) diffuse into the cell via transport
proteins by the membrane potential.
<BR><LI> Anions  (such  as  nitrate)  can  be  taken  in  by coupling their
transport   to   the   inward   diffusion  of  protons  through  a
cotransporter.
<BR><LI> Neutral  solutes  (such  as  sucrose)  can  also  be  imported  by
cotransport with protons down the proton gradient.