Reaction: ABCA4 transports NRPE from photoreceptor outer segment membrane to cytosol
- in pathway: The canonical retinoid cycle in rods (twilight vision)
Bovine studies (Beharry et al. 2004) have indicated NRPE to be the preferred substrate for ABCA4 (ABCR, rim protein, RmP) (Azarian et al. 1998), which acts as an inward-directed retinoid flippase and facilitates the transfer of NRPE to the cytoplasmic side of the disc membrane. This transfer is essential to avoid build up of potentially toxic retinoid intermediates which are implicated in many retinal degenerative diseases (see review Tsybovsky et al. 2010). Defective ABCA4 cannot perform this function leading to impaired vision and blindness disorders such as Stargardt disease (MIM:248200).
Reaction - small molecule participants:
Pi [cytosol]
ADP [cytosol]
NRPE [cytosol]
NRPE [photoreceptor outer segment membrane]
H2O [cytosol]
ATP [cytosol]
Reactome.org reaction link: R-HSA-2466749
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Reaction input - small molecules:
N-retinylidenephosphatidylethanolamine
water
ATP(4-)
Reaction output - small molecules:
hydrogenphosphate
ADP(3-)
N-retinylidenephosphatidylethanolamine
Reactome.org link: R-HSA-2466749