SLC35F6

SLC35F6 (ANT2BP/C2orf18) is an orphan SLC35-family transporter implicated in apoptotic regulation and the control of cancer cell proliferation (PMID:19154410, PMID:40118430). It localizes to lysosomes, with compartment targeting dictated by an EQERLL360 sorting signal in its cytoplasmic C-terminal tail that is both necessary and sufficient for lysosomal delivery, as shown by domain-swap experiments distinguishing it from the recycling-endosome-targeted SLC35F1 (PMID:38928424). SLC35F6 physically interacts with the mitochondrial adenine nucleotide translocase ANT2, and its depletion triggers apoptosis and suppresses growth in pancreatic and hepatocellular carcinoma cells (PMID:19154410, PMID:40118430). In hepatocellular carcinoma, SLC35F6 is a direct target of miR-542-3p, and its knockdown elevates TP53 protein levels, placing it within a miR-542-3p/SLC35F6/TP53 axis governing cell proliferation (PMID:40118430). The transport substrate of SLC35F6 has not been identified in the available corpus, and the molecular link between its lysosomal localization and its mitochondrial/apoptotic functions remains uncharacterized.

1. 2008 Medium

   Established the first physical and functional partner for the orphan protein by showing it binds the mitochondrial nucleotide translocase ANT2 and is required for cancer cell survival.

   Evidence Mitochondrial immunolocalization, co-immunoprecipitation with ANT2, and siRNA knockdown with apoptosis/growth readouts in pancreatic carcinoma cells

   PMID:19154410

   Open questions at the time

   • Interaction shown by single-lab Co-IP without reciprocal or structural validation
   • Mitochondrial localization later contrasted by lysosomal targeting evidence
   • No transport substrate identified
2. 2024 High

   Resolved the steady-state localization of the protein, demonstrating lysosomal targeting driven by a defined C-terminal EQERLL sorting signal that distinguishes it from its paralog SLC35F1.

   Evidence Fluorescence microscopy, C-terminal domain-swap mutants, site-directed mutagenesis of sorting signals, and cell-surface biotinylation

   PMID:38928424

   Open questions at the time

   • Does not reconcile lysosomal localization with the earlier reported mitochondrial localization and ANT2 interaction
   • Transported substrate remains unknown
   • Functional consequence of lysosomal targeting not tested
3. 2024 Low

   Linked SLC35F6 manipulation to apoptotic signaling through the Bcl2/BAX/caspase3 pathway and mitochondrial membrane potential in a non-human model.

   Evidence Functional validation of Bcl2/BAX/caspase3 markers and mitochondrial membrane potential in a piglet diarrhea model

   PMID:39482997

   Open questions at the time

   • Single study with abstract-level methods in a pig model, not independently confirmed in human cells
   • Mechanistic connection between SLC35F6 and the apoptotic pathway not defined
   • No direct molecular target identified
4. 2025 Medium

   Placed SLC35F6 in a regulatory axis controlling proliferation, identifying it as a direct miR-542-3p target whose loss raises TP53 levels in hepatocellular carcinoma cells.

   Evidence siRNA knockdown, western blot for TP53, miR-542-3p target validation, and proliferation assays in H22 and HepG2 cells

   PMID:40118430

   Open questions at the time

   • Direct mutual regulation between SLC35F6 and TP53 explicitly not confirmed by the authors
   • Mechanism by which SLC35F6 alters TP53 levels unknown
   • Single-lab study

• The transport substrate of SLC35F6 and the mechanistic bridge between its lysosomal localization, ANT2 binding, and apoptotic/TP53 regulation remain undefined.
• No transport substrate identified
• Mitochondrial versus lysosomal localization not reconciled
• Causal mechanism linking the protein to Bcl2/BAX/caspase3 and TP53 unresolved