PP_0892 encodes a membrane-associated phospholipase D-family protein with a ClsB-like family assignment and two PLD-like regions. Its physiological phospholipid substrate and contribution to cardiolipin synthesis are not experimentally established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic catalytic activity is too broad for this PLD-family protein. Reason: Use phosphatidyltransferase activity as the cautious function supported by the PLD-family architecture while substrate specificity remains unresolved. Proposed replacements: phosphatidyltransferase activity Supporting Evidence: file:PSEPK/PP_0892/PP_0892-uniprot.txt DR InterPro; IPR001736; PLipase_D/transphosphatidylase. file:PSEPK/PP_0892/PP_0892-uniprot.txt DR Pfam; PF13091; PLDc_2; 2. |
| GO:0008808 cardiolipin synthase activity | IEA GO_REF:0000118 | UNDECIDED | Summary: Exact cardiolipin synthase activity remains unresolved for PP_0892. Reason: TreeGrafter and PANTHER place PP_0892 in a ClsB-like node, but the current UniProt record remains generic and supplies no reaction or experimental substrate evidence. |
| GO:0016020 membrane | IEA GO_REF:0000118 | ACCEPT | Summary: Accept membrane localization for this PLD-domain lipid enzyme candidate. Reason: The PLD-family cardiolipin synthase-like assignment is consistent with a membrane enzyme. Supporting Evidence: file:PSEPK/PP_0892/PP_0892-uniprot.txt PTHR21248:SF23; CARDIOLIPIN SYNTHASE B |
| GO:0030572 phosphatidyltransferase activity | IEA GO_REF:0000117 | ACCEPT | Summary: Accept broad phosphatidyltransferase activity for this PLD-family protein. Reason: The two PLD-like regions support phosphatidyltransferase chemistry, while the exact phospholipid substrates remain unresolved. Supporting Evidence: file:PSEPK/PP_0892/PP_0892-uniprot.txt InterPro; IPR001736; PLipase_D/transphosphatidylase. |
| GO:0032049 cardiolipin biosynthetic process | IEA GO_REF:0000120 | UNDECIDED | Summary: Cardiolipin biosynthesis is plausible but not established for PP_0892. Reason: The process assignment depends on the same computational ClsB-like inference as the unresolved exact molecular function and lacks direct KT2440 evidence. |
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Download this section (compressed HTML)Q: Does PP_0892 synthesize cardiolipin in vivo or act on a different phospholipid substrate?
Experiment: Assay purified PP_0892 against PG, PE, and other phospholipids, and perform deletion/complementation lipidomics in clsA/clsB-deficient backgrounds.
Q88PF8 is an unreviewed phospholipase-family protein assigned to the PANTHER
ClsB subfamily. Its current record contains two Cls-like CDD domains and two
Pfam/SMART PLD-domain calls, but only one PROSITE PLD call
[UniProtKB:Q88PF8, "PTHR21248:SF23; CARDIOLIPIN SYNTHASE B"].
The exact cardiolipin synthase annotation is entirely computational. The
protein is therefore treated as a ClsB-like candidate, not as an established
additional KT2440 pathway implementation. The broad phosphatidyltransferase
assignment is plausible, while exact substrate chemistry remains unresolved.
Purified-protein assays with PG and PE, active-site HKD substitutions, and
lipidomics in clsA/clsB deletion backgrounds would discriminate active
cardiolipin synthesis from another PLD-family function.
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