PSBP1

Summary: PsbP1 is an extrinsic component of PSII located in the thylakoid lumen, docking on the lumenal face of the membrane-embedded PSII complex.

Reason: The thylakoid association is sound - PsbP1 docks on the lumenal face of the membrane-embedded PSII complex, and the PAINT IBD at PTN001584458 is seeded by AT3G55330 (PPL1), a lumen-facing PsbP-family protein associated with the thylakoid membrane. By GO convention a peripheral protein is located in the membrane it is peripheral to, so this term states the same fact as GO:0019898 extrinsic component of membrane with the membrane specified, and it is consistent with the two experimental HDA rows for the same term. The precise functional compartment, chloroplast thylakoid lumen (GO:0009543), is already annotated separately. The retired duplicate review of the same protein (genes/ARATH/AAU94417) had proposed MODIFY to GO:0009543; that is not adopted, since it would only duplicate an existing annotation and discard the membrane-association information.

Summary: PsbP1 is a photosystem II (PSII) oxygen-evolving complex extrinsic protein, not a photosystem I (PSI) protein. Falcon deep research unambiguously and repeatedly assigns At1g06680/PsbP1 to PSII/OEC, with no evidence for any role in PSI assembly. This IBA annotation appears to be an erroneous phylogenetic/paralog propagation (photosystem I rather than photosystem II) and should be removed.

Reason: Removed because PsbP1 is a PSII/OEC subunit; falcon deep research provides no support for photosystem I assembly and the PSII evidence contradicts a PSI role.

Summary: InterPro2GO mapping from the PsbP domain (IPR002683). PsbP helps retain Ca2+ and Cl- at the Mn4CaO5 cluster of the oxygen-evolving complex, but that is a retention role within the complex, not a demonstrated calcium-binding activity of PsbP1 itself.

Reason: The calcium connection is real but indirect. In vitro reconstitution work on higher-plant PsbP (tobacco/spinach PSII) shows that PsbP is needed to retain Ca2+ and Cl- as cofactors of the water-splitting reaction; the Ca2+ itself is ligated in the Mn4CaO5 cluster of the OEC, and the evidence describes PsbP as a retention factor for that site rather than as a calcium-binding protein. The Ca2+ dependency is a property of the OEC, so the OEC complex term and the core function capture this more accurately than a calcium ion binding activity on PsbP1. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE.

Summary: PsbP1 is a lumen-facing extrinsic PSII protein. Falcon deep research places it in the chloroplast thylakoid lumen with evidence for both a soluble lumen pool and a membrane-associated lumen pool near the PSII supercomplex. Core localization.

Reason: Retained as a core location; consistent with PsbP1 as an extrinsic lumenal PSII subunit.

Summary: This is the most specific and accurate cellular component for PsbP1. In plants the oxygen-evolving complex comprises three extrinsic proteins (PsbO, PsbP, PsbQ), and PsbP is one of them. Falcon deep research strongly corroborates that At1g06680/PsbP1 is an OEC-associated extrinsic subunit. Core localization.

Reason: Retained as the most specific core location; PsbP is one of the three plant OEC extrinsic proteins.

Summary: PsbP1 is a peripheral (extrinsic) protein bound to the lumenal face of the membrane-embedded PSII complex; it has no transmembrane segment.

Reason: Accurate description of how PsbP1 associates with the thylakoid membrane from the lumenal side; consistent with the experimental chloroplast thylakoid membrane rows, which state the same peripheral association with the membrane specified. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed ACCEPT; the earlier KEEP_AS_NON_CORE here had only a boilerplate reason, so the duplicate's ACCEPT is adopted.

Summary: PsbP1 was among many proteins recovered in high-throughput salicylic acid-binding screens. No physiological role for salicylic acid binding by PsbP1 has been described.

Reason: The screen result is experimental and is not disputed, but it is not part of PsbP1's core PSII role. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE; adopted over the earlier MARK_AS_OVER_ANNOTATED, whose reason was boilerplate and did not name a more specific term.

Summary: Thylakoid-membrane proteomics detects PsbP1, but as an extrinsic lumenal OEC subunit docked on the lumenal face of PSII rather than as a membrane-intrinsic protein.

Reason: The experimental detection is real and not disputed - thylakoid-membrane fractions recover PsbP1 because it is bound to the lumenal face of the membrane-embedded PSII complex. By GO convention a peripheral protein is located in the membrane it is peripheral to, so this term states the same fact as GO:0019898 extrinsic component of membrane with the membrane specified; it complements, rather than conflicts with, the chloroplast thylakoid lumen annotations (GO:0009543 is already annotated by IEA and HDA, so a MODIFY would add no coverage).

Summary: Experimental proteomic analysis of the lumenal and peripheral thylakoid proteome recovers PsbP1 in the chloroplast thylakoid lumen, the compartment where the PSII oxygen-evolving complex extrinsic proteins act.

Reason: This is the precise functional compartment of PsbP1, which is imported into the lumen by the Tat pathway and docks on the lumenal face of PSII; it is the location asserted in core_functions.

Summary: Proteomic detection of PsbP1 in the thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: Lumen proteome mapping of Arabidopsis chloroplasts detects PsbP1 in the thylakoid lumen.

Reason: Correct location for a lumen-facing extrinsic PSII subunit; the more specific GO:0009543 chloroplast thylakoid lumen is also annotated (IEA and HDA), and this parent term adds no conflicting claim.

Summary: High-throughput proteomic detection of PsbP1 in the apoplast. PsbP1 is an abundant thylakoid-lumen protein, so detection outside its functional compartment may reflect an import intermediate or co-purification; it does not reflect where PsbP1 acts.

Reason: Retained as non-core rather than removed: the detection is an experimental curator annotation and the cached records do not show it was wrong. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed REMOVE as contamination; not adopted for that reason.

Summary: Stromal proteomics recovered PsbP1. PsbP1 is a nuclear-encoded lumenal protein that crosses the stroma during import before Tat-dependent translocation into the lumen, so a stromal pool is expected transiently; the steady-state location is the thylakoid lumen.

Reason: The experimental detection is not disputed, and a transit-intermediate stromal pool is biologically plausible, but the stroma is not where PsbP1 functions. This reconciles the two duplicate reviews: this file had ACCEPT with a boilerplate reason, and genes/ARATH/AAU94417 proposed REMOVE as contamination. REMOVE would overrule an experimental curator annotation without evidence that the detection was wrong, so the conservative KEEP_AS_NON_CORE is used.

Summary: Thylakoid-membrane proteomics detects PsbP1, but as an extrinsic lumenal OEC subunit docked on the lumenal face of PSII rather than as a membrane-intrinsic protein.

Reason: The experimental detection is real and not disputed - thylakoid-membrane preparations recover PsbP1 because it is bound to the lumenal face of PSII. As for the PMID:15322131 row, a peripheral protein is located in the membrane it is peripheral to, so this is consistent with GO:0019898 extrinsic component of membrane and complements the thylakoid lumen annotations.

Summary: Proteomic detection of PsbP1 in the thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: Proteomic detection of PsbP1 in the thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: Proteomic detection of PsbP1 in the chloroplast. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: Proteomic detection of PsbP1 in the chloroplast thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: Stromal proteomics recovered PsbP1. PsbP1 is a nuclear-encoded lumenal protein that crosses the stroma during import before Tat-dependent translocation into the lumen, so a stromal pool is expected transiently; the steady-state location is the thylakoid lumen.

Reason: The experimental detection is not disputed, and a transit-intermediate stromal pool is biologically plausible, but the stroma is not where PsbP1 functions. This reconciles the two duplicate reviews: this file had ACCEPT with a boilerplate reason, and genes/ARATH/AAU94417 proposed REMOVE as contamination. REMOVE would overrule an experimental curator annotation without evidence that the detection was wrong, so the conservative KEEP_AS_NON_CORE is used.

Summary: Proteomic detection of PsbP1 in the thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: High-throughput proteomic detection of PsbP1 in the chloroplast envelope. PsbP1 is an abundant thylakoid-lumen protein, so detection outside its functional compartment may reflect an import intermediate or co-purification; it does not reflect where PsbP1 acts.

Reason: Retained as non-core rather than removed: the detection is an experimental curator annotation and the cached records do not show it was wrong. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed REMOVE as contamination; not adopted for that reason.

Summary: PsbP1 was recovered in a leaf RNA interactome capture screen. The mature protein resides in the thylakoid lumen, a compartment topologically separate from the stroma and cytosol that contain mRNA, and no mRNA-binding role for PsbP1 has been described.

Reason: The capture result is not disputed, but an mRNA-binding function is hard to reconcile with a lumenal location and is not supported by any functional study. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE; MARK_AS_OVER_ANNOTATED is kept because of the compartment argument above.

Summary: High-throughput proteomic detection of PsbP1 in the extracellular region. PsbP1 is an abundant thylakoid-lumen protein, so detection outside its functional compartment may reflect an import intermediate or co-purification; it does not reflect where PsbP1 acts.

Reason: Retained as non-core rather than removed: the detection is an experimental curator annotation and the cached records do not show it was wrong. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed REMOVE as contamination; not adopted for that reason.

Summary: Proteomic detection of PsbP1 in the chloroplast. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: The detection is consistent with PsbP1's known location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543; because GO:0009543 is already annotated, a MODIFY would only duplicate it, so the correct parent term is accepted.

Summary: AtSubP prediction of chloroplast localization. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: Correct prediction. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543, which is already annotated.

Summary: Split-ubiquitin yeast two-hybrid interaction between the PsbP1 precursor and the chloroplast preprotein import receptors atToc159/atToc132. This reflects PsbP1 being an import substrate (transit peptide recognition), not a binding activity of the mature protein.

Reason: The interaction is real but describes the receptors' substrate specificity; the binding activity belongs to the Toc receptors, not to PsbP1. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE; MARK_AS_OVER_ANNOTATED is kept because this is substrate recognition by the import machinery.

Summary: PsbP1 was identified in a study of low-abundance leaf proteins; the poly(U) RNA binding assignment comes from that enrichment workflow. As for mRNA binding, a lumenal protein has no access to cellular RNA and no RNA-binding role for PsbP1 has been described.

Reason: Not disputed as an observation, but unlikely to represent a physiological activity of the mature lumenal protein. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE; MARK_AS_OVER_ANNOTATED is kept for the compartment reason.

Summary: PsbP1 encodes the 23-kDa extrinsic subunit of the PSII oxygen-evolving complex, which participates directly in the light-driven water oxidation step of the photosynthetic light reactions.

Reason: As an OEC subunit that retains the Ca2+ and Cl- cofactors of water oxidation and stabilizes the Mn cluster, PsbP does part of the work of the PSII light reaction; loss of PsbP in higher plants (tobacco RNAi, PMID:16244145) collapses PSII quantum yield and destabilizes the Mn cluster. This is the core BP of the gene. The acts_upstream_of_or_within qualifier on this TAS row understates a structural PSII subunit's participation (see suggested_questions).

Summary: PsbP1 is a peripheral (extrinsic) protein bound to the lumenal face of the membrane-embedded PSII complex; it has no transmembrane segment.

Reason: Accurate description of how PsbP1 associates with the thylakoid membrane from the lumenal side; consistent with the experimental chloroplast thylakoid membrane rows, which state the same peripheral association with the membrane specified. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed ACCEPT; the earlier KEEP_AS_NON_CORE here had only a boilerplate reason, so the duplicate's ACCEPT is adopted.

Summary: Experimental localization of PsbP1 to the chloroplast thylakoid. Correct but general location for a thylakoid-lumen OEC subunit; the precise compartment (GO:0009543 chloroplast thylakoid lumen) is annotated separately.

Reason: Correct location. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009543, which is already annotated.

Summary: PsbP1 is a classical extrinsic, lumen-facing subunit of photosystem II. The more specific GO:0009654 oxygen evolving complex is also annotated.

Reason: Correct complex membership. This row replaces the earlier GO_REF:0000120 row for the same term, which is no longer in GOA. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0009654; since GO:0009654 is already annotated to the gene, a MODIFY would only duplicate it, so the correct parent is accepted.

Summary: ARBA rule placing PsbP1 in the chloroplast thylakoid. Correct; the precise compartment is the thylakoid lumen, which is also annotated.

Reason: Correct, if general, location for a thylakoid-lumen OEC subunit; consistent with the IDA and HDA rows for the same term.

Summary: PsbP1 is an oxygen-evolving complex subunit and functions in photosynthesis. The more specific GO:0019684 photosynthesis, light reaction is also annotated (TAS).

Reason: Correct process. This row replaces the earlier GO_REF:0000120 row for the same term, which is no longer in GOA. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed MODIFY to GO:0019684; that term is already annotated, so the correct parent is accepted rather than duplicated.

Summary: Split-ubiquitin yeast two-hybrid interaction between the PsbP1 precursor and the chloroplast preprotein import receptors atToc159/atToc132. This reflects PsbP1 being an import substrate (transit peptide recognition), not a binding activity of the mature protein.

Reason: The interaction is real but describes the receptors' substrate specificity; the binding activity belongs to the Toc receptors, not to PsbP1. Reconciled with the retired duplicate review genes/ARATH/AAU94417 (same protein, Q42029), which proposed KEEP_AS_NON_CORE; MARK_AS_OVER_ANNOTATED is kept because this is substrate recognition by the import machinery.