Reaction: SLC24A1 exchanges 4Na+ for Ca2+, K+
- in pathway: Activation of the phototransduction cascade
Intracellular Ca2+ is extruded from the outer segment by a Na+/Ca2+, K+ exchanger (NCKX1 encoded by SLC24A1) (Tucker et al. 1998). Operation of the exchanger is electrogenic; 4 Na+ enter and 1 K+ exits for every Ca2+ removed for a net movement of 1 positive charge inward per duty cycle. In bright light, when all of the CNG channels are closed, the exchanger continues to remove Ca2+, reducing intracellular Ca2+ by an order of magnitude. Mutations in SLC24A1 can give rise to recessive congenital stationary night blindness (Riazuddin et al. 2010).
Reaction - small molecule participants:
K+ [extracellular region]
Na+ [cytosol]
Ca2+ [extracellular region]
K+ [cytosol]
Ca2+ [cytosol]
Na+ [extracellular region]
Reactome.org reaction link: R-HSA-2514891
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Reaction input - small molecules:
potassium(1+)
calcium(2+)
sodium(1+)
Reaction output - small molecules:
potassium(1+)
sodium(1+)
calcium(2+)
Reactome.org link: R-HSA-2514891