PP_0076 is a signal-peptide-bearing periplasmic substrate-binding protein in the choline/glycine-betaine transporter binding-protein family. Its physiological ligand and membrane-transport partner are unresolved; current evidence does not establish an ABC complex or direct transmembrane transporter activity for this soluble protein.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0015871 choline transport | IEA GO_REF:0000002 | UNDECIDED | Summary: Choline transport is plausible from family membership but is not established for PP_0076. Reason: The annotation is transferred from the choline-transporter substrate-binding family. No target-specific study distinguishes choline from choline-O-sulfate, glycine betaine, or another related ligand. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-goa.tsv GO:0015871 choline transport file:PSEPK/PP_0076/PP_0076-deep-research-openscientist.md No direct biochemical characterization of PP_0076 itself. |
| GO:0022857 transmembrane transporter activity | IEA GO_REF:0000002 | REMOVE | Summary: A soluble periplasmic binding protein does not itself translocate substrate across a membrane. Reason: PP_0076 has a cleavable signal peptide and a periplasmic substrate-binding-protein architecture but no transmembrane segment. Transport-process participation is separable from enabling transporter molecular activity. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-uniprot.txt FT SIGNAL 1..20 file:PSEPK/PP_0076/PP_0076-uniprot.txt InterPro; IPR007210; ABC_Gly_betaine_transp_sub-bd. |
| GO:0033265 choline binding | IEA GO_REF:0000002 | UNDECIDED | Summary: Exact choline binding remains unresolved for the target protein. Reason: The term is a family-based inference, and neither direct ligand-binding data nor target-specific genetics resolves the physiological ligand. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-goa.tsv GO:0033265 choline binding |
| GO:0042597 periplasmic space | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: The signal peptide and binding-protein architecture support a periplasmic location. Reason: Periplasmic localization is valid but ancillary to the unresolved substrate-binding role. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-uniprot.txt FT SIGNAL 1..20 |
| GO:0043190 ATP-binding cassette (ABC) transporter complex | IEA GO_REF:0000002 | UNDECIDED | Summary: Family and syntenic-locus evidence are compatible with an ABC substrate-binding role, but no cognate KT2440 ABC assembly has been established. Reason: The target has ABC substrate-binding-family architecture and a characterized Pseudomonas homolog is described as a potential ABC substrate-binding protein. However, PP_0075 is an SLC26A/SulP-STAS permease, and the cognate KT2440 permease and ATPase could be encoded elsewhere. Current evidence neither establishes nor excludes ABC-complex membership. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-uniprot.txt InterPro; IPR017783; ABC_choline_sub-bd. PMID:21369825 substrate-binding ABC transporter protein (betD) |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | ACCEPT | Summary: Retain generic transport-process participation for a periplasmic transporter binding protein. Reason: The substrate-binding-protein architecture supports participation in a transport process, although the transported ligand and membrane partner remain unresolved. Supporting Evidence: file:PSEPK/PP_0076/PP_0076-uniprot.txt InterPro; IPR007210; ABC_Gly_betaine_transp_sub-bd. |
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Download this section (compressed HTML)Q: Which ligand binds PP_0076 in vivo, and does PP_0076 function with PP_0075 or a different membrane transporter?
Experiment: Measure purified PP_0076 binding to choline, choline-O-sulfate, glycine betaine, and related osmolytes, then pair deletion/complementation genetics with uptake assays and interaction tests against PP_0075.
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