3. Organic acids:

With context to organic acids, malate transport across the vacuolar membrane has been studied most intensively. This is due to the central role of malate in plant metabolism. The uptake of maltate is mainly governed by the electrical component of the electrochemical potential generated by the proton pumps. This channel also mediates uptake of succinate, fumarate, and oxaloacetate. The malate channel is not affected by cytosolic Ca²⁺ or ATP and it is a 32 kDa subunit protein. Citrate crosses the tonoplast using the same transporter as malate.

4. Inorganic anions:

The H⁺ pumps generate a positive potential inside the vacuole, which is the driving force for anion movements. Anion-dependent dissipation of a proton-pump generated by anions revealed that NO₃^– permeates more rapidly than Cl^– and SO₄^– whereas HPO₄^2–   crossed the tonoplast considerably slowly.

Chloride:

An ATP-dependent Cl^– uptake was studied in barley mesophyll vacuoles.  Later a vacuolar Cl^– channel (VCL) was identified in Vicia faba guard cells which is activated by a dependent protein kinase (CDPK) in the presence of ATP and Ca²⁺and, to a weaker extend (22%), by protein kinase A. The VCL channel was activated at physiological potentials enabling Cl^– uptake into vacuoles.

Nitrate:
Amongst the anions it exhibits the highest permeability through the vacuolar membrane. It was concluded in one of the experiment that a membrane potential driven nitrate transporter, a NO₃^– /H⁺ antiporter is present on the tonoplast.

Sulphate:

Using tonoplast vesicles, it has been shown that SO₄^2– and HPO₄^2– anions cross the tonoplast slowly as compared to NO₃^– or Cl^–. . It has been found that SO₄^2– uptake is stimulated by Mg⁺ -ATP.

Phosphate:

Pi starvation leads to an efflux of Pi from the vacuole. It has been shown that Pi concentrations in the cytosol are maintained at a constant level in Acer pseudoplatanus cells using ³¹P NMR.  

5. Inorganic cation:

The membrane potential of the cytosol with respect to the vacuole is negative (20–40 mV). This implies that cations are excluded from the vacuole unless transport is coupled to an energy-dependent uptake mechanism.

Potassium:

Several channels exhibiting potassium permeability have been described. The first channel demonstrated for vacuolar membrane was called SV (slow activating vacuolar) channel. This channel is a slow activated channel and is associated with Ca²⁺ and calmodulin-induced K⁺ and Ca²⁺ fluxes. These channels have been reported for the permeability of Na⁺ if Ca²⁺ concentrations are increased by a signal. Secondly, FV (fast vacuolar) channel activates instantaneously in response to voltage changes. These channels may allow the release of K⁺ at low Ca²⁺ concentrations.Thirdly, the vacuolar K⁺ (VK) channel is activated instantaneously but it can be distinguished from the FV channel. It is voltage independent and fully activated at low cytosolic pH.

A K⁺/H⁺ antiport mechanism has been also reported for tonoplast enriched fractions from zucchini, Brassica napushypocotyls, and Atriplex.