PP_0075 is a multi-pass SLC26A/SulP-family membrane transporter with a cytoplasmic STAS domain. It lies next to the choline-sulfatase gene betC, but its transported substrate, coupling mechanism, and proposed role in choline-O-sulfate uptake have not been established experimentally.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: The multi-pass architecture supports membrane localization; the specific membrane is the cytoplasmic (plasma) membrane. Reason: The predicted membrane-spanning segments, SLC26A/SulP transport domain and cytoplasmic STAS domain support a bacterial inner-membrane transporter. Thus plasma membrane (GO:0005886) is the supported refinement of membrane. This is an architecture-based localization inference for Q88RQ4, not a localization assay or a universal claim about Gram-negative membrane organization. Proposed replacements: plasma membrane Supporting Evidence: file:PSEPK/PP_0075/PP_0075-uniprot.txt FT TRANSMEM 42..65 file:PSEPK/PP_0075/PP_0075-uniprot.txt FT TRANSMEM 385..416 file:PSEPK/PP_0075/PP_0075-uniprot.txt InterPro; IPR011547; SLC26A/SulP_dom. |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | ACCEPT | Summary: Accept generic transmembrane transport without assigning a specific cargo. Reason: Nine predicted membrane-spanning segments and the SLC26A/SulP family assignment support a transport role. Neither the submitted product name nor genomic adjacency establishes choline-O-sulfate specificity. Supporting Evidence: file:PSEPK/PP_0075/PP_0075-uniprot.txt InterPro; IPR001902; SLC26A/SulP_fam. file:PSEPK/PP_0075/PP_0075-deep-research-openscientist.md PP_0075 encodes an integral inner-membrane secondary transporter belonging to the **SulP / SLC26 anion-permease superfamily**. |
| GO:0022857 transmembrane transporter activity | ISS file:PSEPK/PP_0075/PP_0075-uniprot.txt | NEW | Summary: Add the generic molecular activity implied by the multi-pass SLC26A/SulP architecture. Reason: The fetched GOA set contains the transport process but no molecular function. A generic transporter activity is defensible while exact cargo specificity remains unresolved. Supporting Evidence: file:PSEPK/PP_0075/PP_0075-uniprot.txt InterPro; IPR001902; SLC26A/SulP_fam. |
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Download this section (compressed HTML)Q: What solute does PP_0075 transport, and does it functionally couple to the adjacent PP_0076 binding protein?
Experiment: Measure uptake of choline-O-sulfate, sulfate, choline, and related solutes in clean PP_0075 deletion and complementation strains, then reconstitute transport in proteoliposomes.
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