SLC37A3

SLC37A3 is a membrane transporter of the SLC37 sugar-phosphate/phosphate exchanger family whose principal characterized role is in lysosomal export of nitrogen-containing bisphosphonates (N-BPs) (PMID:29745899, PMID:24745989). At the lysosome, SLC37A3 forms a complex with ATRAID and is required to release N-BPs that have entered cells via fluid-phase endocytosis from the lysosome into the cytosol, enabling these drugs to reach their cytosolic target in the mevalonate pathway (PMID:29745899). While the other three SLC37 family members are Pi-linked glucose-6-phosphate antiporters, the intrinsic physiological transport substrate of SLC37A3 has not been defined in the available corpus (PMID:24745989). Homozygous loss-of-function variants in SLC37A3, including variants that cause exon skipping, cause autosomal recessive retinitis pigmentosa (PMID:35486108). Beyond these findings, the molecular basis of SLC37A3 transport activity and its role in retinal degeneration have not been characterized in the available corpus.

1. 2014 Medium

   Establishing where SLC37A3 sits among transporters set the initial expectation that it is a sugar-phosphate/phosphate exchanger, while flagging that its substrate was uniquely undefined within the family.

   Evidence Sequence homology and functional comparison across SLC37 family members

   PMID:24745989

   Open questions at the time

   • No direct transport assay identifying a substrate
   • ER localization inferred from family membership rather than measured for SLC37A3
   • Does not address physiological cargo or directionality
2. 2018 High

   A genome-wide screen for N-BP sensitivity revealed an unexpected functional role: SLC37A3 partners with ATRAID at the lysosome to export endocytosed N-BPs into the cytosol, answering how these drugs escape the lysosome to reach their target.

   Evidence CRISPRi genome-wide screen with co-localization, complex identification, and functional N-BP rescue assays in human cells

   PMID:29745899

   Open questions at the time

   • Whether N-BP export reflects the native physiological substrate or an opportunistic activity is unresolved
   • Stoichiometry and transport mechanism of the SLC37A3-ATRAID complex not defined
   • Reconciliation with the earlier ER-localization assignment not addressed
3. 2022 Medium

   Human genetics tied SLC37A3 to disease, showing that complete loss of function causes autosomal recessive retinitis pigmentosa and establishing the gene as essential for retinal health.

   Evidence Exome sequencing of an inherited retinal disease cohort with transcript (exon skipping) and protein expression analysis across multiple families

   PMID:35486108

   Open questions at the time

   • Mechanism linking SLC37A3 loss to photoreceptor degeneration not elucidated
   • Whether the retinal phenotype involves a transport substrate distinct from N-BPs is unknown
   • No animal model establishing causality
4. 2025 Low

   A regulatory context was added by placing SLC37A3 downstream of a lncRNA/miRNA axis controlling chronic lymphocytic leukemia cell proliferation.

   Evidence RT-qPCR, TUSC7 overexpression, RNA pulldown, siRNA silencing, and rescue assays measuring proliferation/apoptosis in CLL cells

   PMID:40056063

   Open questions at the time

   • Single-lab study; molecular mechanism of SLC37A3 action in CLL not defined
   • Whether transport activity underlies the proliferative phenotype unknown
   • No independent confirmation of the TUSC7/miR-211-5p/SLC37A3 axis

• The intrinsic physiological transport substrate of SLC37A3 and the mechanism connecting its loss to retinal degeneration remain unknown.
• No direct biochemical identification of a native substrate
• No structural model of the transporter or the SLC37A3-ATRAID complex
• Causal mechanism in retinitis pigmentosa undefined