Potassium balance

How it works

1. A TrkH-family potassium uptake protein with its TrkA C-terminal partner is annotated, alongside a separate potassium channel family protein.
2. Trk systems accumulate K+ using the membrane potential, while channel proteins allow passive flux. Together they set turgor and offset the charge imbalance created by other transport.
3. The two mechanisms have opposite energetics, which is why they are grouped rather than merged. Neither annotation states the selectivity or conductance that would have to be measured.
4. Potassium-channel and TrkH/TrkA-family annotations identify routes that can contribute to potassium balance. Channels, uptake components and regulatory domains have different roles.
5. Transport changes the intracellular potassium pool in response to available gradients, substrate concentrations and regulation. Changes in ion content also affect osmotic and electrical conditions.
6. Steady cellular conditions result from regulated transport and other solute systems together. These annotations alone do not specify the in vivo direction, transport rate or target potassium concentration.

Grouped by the atlas’s curated pathway map. The table order is not a proven reaction order.

Its proteins

Origins

How could a cell hold potassium inside before potassium transporters existed?

The wider question for this part of the cell: origins for pulling nutrients in from outside.

Sources

• Atlas pathway grouping from the VF5 reference-genome system map (Deckert et al. 1998; Braakman & Smith 2014)