Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Automatic assignment of GO terms using logical inference, based on on inter-ontology links
Combined Automated Annotation using Multiple IEA Methods
Cloning and expression of SLC10A4, a putative organic anion transport protein.
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SLC10A4 transfected into CHO cells shows no significant sodium-dependent taurocholate uptake relative to untransfected cells, despite reaching the plasma membrane and intracellular compartments.
"Functional analysis of SLC10A4 showed no significant taurocholate uptake in the presence of sodium when compared to untransfected CHO cells."
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The expressed protein is detected both at the plasma membrane and in intracellular compartments.
"immunoblotting analysis and immunofluorescence staining demonstrated a 49-kDa protein that is expressed at the plasma membrane and intracellular compartments"
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The authors' own conclusion is that SLC10A4 has no capacity to transport taurocholate relative to SLC10A1.
"To date, we have shown that this protein has no capacity to transport taurocholate relative to SLC10A1"
Cloning and molecular characterization of the orphan carrier protein Slc10a4: expression in cholinergic neurons of the rat central nervous system.
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Slc10a4 is a 437-residue seven-transmembrane protein with an extracellular N-terminus and cytoplasmic C-terminus.
"The rat Slc10a4 protein consists of 437 amino acids and exhibits a seven transmembrane domain topology with N(exo)/C(cyt)trans-orientation of the N- and C-terminal ends."
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Slc10a4 transports none of the NTCP substrates in HEK293 cells or Xenopus oocytes.
"Despite its close phylogenetic relationship to Ntcp, Slc10a4 showed no transport activity for the Ntcp substrates taurocholate, estrone-3-sulfate, dehydroepiandrosterone sulfate, and pregnenolone sulfate when expressed in HEK293 cells or Xenopus laevis oocytes."
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Slc10a4 does not transport choline either, excluding the obvious candidate suggested by its cholinergic expression.
"Slc10a4 also did not transport choline, which is a substrate of CHT1."
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Slc10a4 is expressed in cholinergic neurons, co-localizing with ChAT, VAChT and CHT1.
"Co-localization studies with the cholinergic marker proteins choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), and high-affinity choline transporter (CHT1) demonstrated expression of Slc10a4 in cholinergic neurons."
Co-expression studies of the orphan carrier protein Slc10a4 and the vesicular carriers VAChT and VMAT2 in the rat central and peripheral nervous system.
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Slc10a4 resides in synaptic vesicles, co-localizing with synaptophysin, VAChT and VMAT2 in rat brain vesicle preparations.
"Western blot and immunoprecipitation experiments with rat brain vesicle preparations revealed that the Slc10a4 protein was expressed in synaptic vesicles where it co-localized with synaptophysin, VAChT and VMAT2."
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Slc10a4 is also present in the secretory granules of peritoneal and tissue mast cells.
"Slc10a4 expression was also detected in granules of rat peritoneal and tissue mast cells using immunofluorescence and electron microscopy."
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Slc10a4 has no transport activity for bile acids despite its close phylogenetic relationship to Ntcp.
"Slc10a4 has a close phylogenetic relationship with the liver bile acid carrier Ntcp (Slc10a1), but has no transport activity for bile acids."
Homo- and hetero-dimeric architecture of the human liver Na⁺-dependent taurocholate co-transporting protein.
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SLC10A4 forms heteromeric complexes with NTCP in co-expression systems.
"SLC10A4 and SLC10A6 co-immunoprecipitated with NTCP, demonstrating that heteromeric complexes can be formed between SLC10A family members in vitro."
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Co-expressing SLC10A4 reduces NTCP plasma-membrane abundance and NTCP-mediated taurocholate uptake, so the effect on bile salt transport is negative and acts through a partner's trafficking.
"Expression of SLC10A4 and NTCP Y307X resulted in a reduction of NTCP abundance at the plasma membrane and NTCP-mediated taurocholate uptake"
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The authors attribute the effect on bile salt uptake to impaired NTCP plasma membrane trafficking rather than to any transport activity of the partner.
"Bile salt uptake is influenced by heterodimerization when this impairs NTCP plasma membrane trafficking."
The synaptic protein encoded by the gene Slc10A4 suppresses epileptiform activity and regulates sensitivity to cholinergic chemoconvulsants.
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Slc10a4 null mice show spontaneous hippocampal gamma oscillations and selective cholinergic hypersensitivity, implicating the protein in cholinergic synaptic function.
"In contrast to wild type mice, gamma oscillations occurred spontaneously in hippocampal slices from Slc10a4 null mice."
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Slc10a4 is a presynaptic carrier protein of cholinergic and monoaminergic terminals.
"The gene Slc10A4 encodes a recently described carrier protein present in pre-synaptic terminals of cholinergic and monoaminergic neurons."
SLC10A4 is a protease-activated transporter that transports bile acids.
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SLC10A4 has no baseline bile acid transport activity.
"SLC10A4 belongs to the sodium bile acid cotransporter family, but has no transport activity for bile acids."
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Thrombin treatment of TE671 cells increases lithocholic and taurocholic acid uptake, and SLC10A4 knockdown abolishes that increase.
"After RNA interference treatment for SLC10A4, bile acid uptake was also quantified. In consequence, increases in the LCA and TCA uptake did not occur."
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The conclusion is hedged and conditional on proteolytic activation; no sodium dependence, stoichiometry or kinetics of symport is reported.
"Therefore, SLC10A4 may have low activity but becomes activated by proteases, including thrombin, following cleavage."
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Thrombin cleaves the extracellular N-terminus of SLC10A4, an experiment that implies a surface-exposed pool of the protein.
"After thrombin treatment, western blotting and immunofluorescence staining demonstrated that the N-terminus of SLC10A4 might be cleaved."
Distribution of SLC10A4, a synaptic vesicle protein in the human brain, and the association of this protein with Alzheimer's disease-related neuronal degeneration.
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In aged human brain SLC10A4 is expressed particularly in cholinergic and monoaminergic neurons and the lateral geniculate body.
"The protein was ubiquitously expressed, particularly in the cholinergic and monoaminergic neurons and in the lateral geniculate body."
SLC10A4 is a vesicular amine-associated transporter modulating dopamine homeostasis.
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SLC10A4 is on the same synaptic vesicles as VAChT or VMAT2.
"We show that SLC10A4 is localized on the same synaptic vesicles as either vesicular acetylcholine transporter or vesicular monoamine transporter 2."
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No direct dopamine transport by SLC10A4 was found, but vesicles lacking it load dopamine less efficiently.
"We did not find evidence for direct transport of dopamine by SLC10A4; however, synaptic vesicle preparations lacking SLC10A4 showed decreased dopamine vesicular uptake efficiency."
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Vesicles from SLC10A4-overexpressing mice are more acidic, so lumenal acidification scales with SLC10A4 dose in both directions.
"Furthermore, we observed an increased acidification in synaptic vesicles isolated from mice overexpressing SLC10A4."
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In the brain SLC10A4 is exclusively expressed in presynaptic vesicles of monoaminergic and cholinergic neurons and has a regulatory role in dopamine homeostasis.
"Here we report that the orphan transporter SLC10A4, which in the brain is exclusively expressed in presynaptic vesicles of monoaminergic and cholinergic neurons, has a regulatory role in dopamine homeostasis."
A role for solute carrier family 10 member 4, or vesicular aminergic-associated transporter, in structural remodelling and transmitter release at the mouse neuromuscular junction.
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Neuromuscular junctions lacking SLC10A4/VAAT are structurally remodelled and show altered spontaneous and evoked transmitter release and aberrant short-term plasticity.
"NMJs lacking VAAT had fewer branch points, whereas endplates showed an increased number of islands."
Expression, sorting and transport studies for the orphan carrier SLC10A4 in neuronal and non-neuronal cell lines and in Xenopus laevis oocytes.
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A systematic fourteen-substrate screen with positive controls found no transport activity for SLC10A4.
"SLC10A4 failed to show transport activity for dopamine, serotonin, norepinephrine, histamine, acetylcholine, choline, acetate, aspartate, glutamate, gamma-aminobutyric acid, pregnenolone sulfate, dehydroepiandrosterone sulfate, estrone-3-sulfate, and adenosine triphosphate, at least in the transport assays used."
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Wild-type SLC10A4 does not reach the plasma membrane efficiently in CAD or HEK293 cells; plasma-membrane delivery had to be engineered by replacing its C-terminus with that of NTCP.
"When the C-terminus of SLC10A4 was replaced by the homologous sequence of NTCP, the SLC10A4-NTCP chimeric protein revealed clear plasma membrane expression in CAD and HEK293 cells."
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The plasma-membrane-targeted chimera is still inactive, excluding mislocalization as the explanation for the negative transport results.
"But this chimera also did not show any transport activity, even when the N-terminal domain of SLC10A4 was deleted by mutagenesis."
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SLC10A4 shows a vesicle-like expression pattern in neuronal cell lines, unchanged by differentiation.
"We detected a vesicle-like expression pattern of the SLC10A4 protein in the neuronal cell lines SH-SY5Y and CAD."
SLC10A4 regulates IgE-mediated mast cell degranulation in vitro and mast cell-mediated reactions in vivo.
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Mast cells lacking SLC10A4 release fewer granule-associated mediators after IgE/antigen stimulation, while granule development and lipid mediator release are normal.
"Slc10a4 -/- bone marrow-derived mast cells (BMMCs) had a significant reduction in the release of granule-associated mediators in response to IgE/antigen-mediated activation"
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The substrate of SLC10A4 remains unidentified despite substantial effort.
"In spite of significant efforts, the substrate(s) of SLC10A4 still essentially remains unknown"
Homo- and heterodimerization is a common feature of the solute carrier family SLC10 members.
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SLC10A4 is one of four orphan carriers in the SLC10 family.
"the steroid sulfate transporter SOAT as well as four orphan carriers (SLC10A3, SLC10A4, SLC10A5 and SLC10A7)"
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SLC10A4 heterodimerizes and co-localizes with NTCP, confirmed by co-immunoprecipitation.
"NTCP co-localized with SLC10A4, SLC10A5, SOAT and SLC10A7. This co-localization was most pronounced for SLC10A4 and was additionally confirmed by co-immunoprecipitation."
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SLC10 carrier co-expression decreases NTCP taurocholate transport, so heterodimerization has functional consequences for the partner.
"Interestingly, SLC10 carrier co-expression decreased the taurocholate transport function of NTCP for most of the analyzed constructs, indicating that SLC10 carrier heterodimerization is of functional relevance."
A reference map of the human binary protein interactome.
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HuRI is a proteome-scale yeast two-hybrid screen, so its hits are binary interaction detections rather than evidence of any particular molecular function.
"Specifically, yeast two-hybrid (Y2H) represents the only binary PPI assay that can be operated at sufficient throughput to systematically screen the human proteome for binary PPIs."
SLC10 pocket-conservation analysis: NTCP sodium and preS1 sites across the human family
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SLC10A4 retains every side-chain sodium ligand of NTCP: 11 of 12 sodium-contacting positions are identical and the single substitution (C260 to S338) is at a position that contacts sodium only through a main-chain atom, so its orphan status is not explained by degeneration of the ion-coupling site.
"**SLC10A4's single substitution is C260→S338, and position 260 is a main-chain
contact — so every side-chain sodium ligand is conserved.**"
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In the NTCP bile-salt pocket (defined from bound glycochenodeoxycholate in 7ZYI) SLC10A4 keeps all three polar anchors N103, N262 and Q264 but remodels the hydrophobic lining, including T203 to F281 which introduces a bulky aromatic.
"So SLC10A4 keeps the polar recognition triad but remodels the hydrophobic
lining, with T203→F281 placing a bulky aromatic in the pocket"
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The myristoyl/preS1 pocket of NTCP is not retained in any human paralogue, consistent with HBV receptor function being NTCP-specific.
"The myristoyl
(HBV preS1 anchor) pocket is NTCP-specific; no paralogue retains it."
OpenScientist focused report on SLC10A4 sodium-site retention
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Focused audit found that SLC10A4 retains the NTCP sodium-coordination machinery, so its orphan status is not explained by wholesale Na+-site degeneration.
"SLC10A4 **retains** the complete sodium-coordination machinery"