1.A.1.7.7
Chloroplast thylakoid two-pore calcium and proton-activated K⁺ channel, TPK3 of 436 aas and 4 TMSs.  Mediates ion counterbalancing, influencing photosynthetic llight utilization (Carraretto et al. 2013).  Reviewed by González et al. 2014.  This two-pore potassium channel modulates the proton motive force (pmf) necessary to convert photochemical energy into physiological functions. It mediates the potassium efflux from the thylakoid lumen required for the regulation of the transmembrane electrical potential, the enhancement of the pH gradient for ATP synthesis, the regulation of electron flow, and pH-mediated photoprotective responses (Carraretto et al. 2013). It has multiple functions under drought stress (Corti et al. 2023).