Solute transport.

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