Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005634 nucleus	IBA GO_REF:0000033	REMOVE	Summary: IBA annotation based on phylogenetic inference from other PPEF family members. However, the 2001 study by Ramulu and Nathans (PMID:11312268) found CePPEF to be membrane-associated via lipid modifications and localized to neuronal cell bodies, dendrites, axons, and cilia. No nuclear localization was observed in C. elegans. The 2024 study (PMID:39550471) confirms ciliary localization. Nuclear localization may be an artifact of heterologous expression systems or represent a minor non-conserved localization in other species. Reason: No experimental evidence supports nuclear localization of PEF-1 in C. elegans. Both PMID:11312268 and PMID:39550471 show exclusive membrane/ciliary localization in sensory neurons. The phylogenetic inference may not apply to this species. Supporting Evidence: PMID:11312268 In transgenic C. elegans and in transfected 293 cells, CePPEF is membrane-associated, and the N terminus of CePPEF is necessary and sufficient for this membrane association. PMID:39550471 we found the PEF-1::GFP protein to be concentrated within the cilium, but in a region distal to the transition zone (TZ), which represents the proximal-most region of the axoneme file:worm/pef-1/pef-1-deep-research-falcon.md model: Edison Scientific Literature
GO:0005829 cytosol	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: IBA annotation based on phylogenetic inference. While some cytosolic localization may occur, the predominant localization in C. elegans is membrane-associated and ciliary. The protein requires myristoylation and palmitoylation for proper localization. Cytosolic localization is likely minimal and not the primary site of function. Reason: While membrane association is the predominant localization, some cytosolic presence may occur during protein synthesis/transport. However, the core function is at cilia and cell membrane. The IBA inference from other species may reflect different localization patterns in those organisms. Supporting Evidence: PMID:11312268 In transgenic C. elegans and in transfected 293 cells, CePPEF is membrane-associated
GO:0004722 protein serine/threonine phosphatase activity	IBA GO_REF:0000033	ACCEPT	Summary: Core molecular function of PEF-1 supported by sequence homology to the RdgC/PPEF family, presence of PPP phosphatase domain, and catalytic residues. The protein contains a well-characterized metallophos domain with manganese-binding sites essential for catalysis. UniProt annotates EC 3.1.3.16 activity. Reason: Protein serine/threonine phosphatase activity is the defining molecular function of the PPEF family. PEF-1 contains all necessary catalytic domains and cofactor binding sites. This is strongly supported by phylogenetic analysis and domain architecture. Supporting Evidence: PMID:11312268 The RdgC/PPEF family of serine/threonine protein phosphatases is distinguished by the presence of C-terminal EF-hands and neuron-specific expression, including frequent expression in primary sensory neurons
GO:0004721 phosphoprotein phosphatase activity	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro domain IPR012008. This is a parent term of GO:0004722 (protein serine/threonine phosphatase activity). The more specific child term is already annotated with IBA evidence. Reason: This broader term is consistent with the protein's function and is appropriately inferred from domain architecture. The IEA annotation is valid alongside the more specific IBA annotation for GO:0004722.
GO:0004722 protein serine/threonine phosphatase activity	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation based on Rhea reaction mapping and EC number. This duplicates the IBA annotation but with different evidence source. Both are valid. Reason: This annotation from reaction/EC mapping provides independent support for the core phosphatase function. Duplicate GO IDs with different evidence codes are acceptable.
GO:0005506 iron ion binding	IEA GO_REF:0000002	REMOVE	Summary: IEA annotation from InterPro domain IPR012008. However, PPP phosphatases typically use manganese, not iron, as the catalytic metal. UniProt specifically annotates manganese binding for this protein based on similarity to P36873. Iron binding is not established for PPEF family members. Reason: This is likely an incorrect inference. PPEF family phosphatases use manganese as the catalytic metal ion. UniProt annotation and experimental evidence from related proteins indicate manganese binding, not iron. The InterPro inference may be overly broad.
GO:0005509 calcium ion binding	IEA GO_REF:0000002	ACCEPT	Summary: Core function supported by experimental evidence. PEF-1 contains three EF-hand domains that bind calcium. Ramulu and Nathans (2001) demonstrated calcium binding experimentally using recombinant protein. Reason: Calcium binding is a defining feature of the PPEF family and has been experimentally verified for CePPEF. The EF-hand domains (residues 546-581, 629-664, 669-704) bind 1-2 calcium ions per protein. Supporting Evidence: PMID:11312268 A recombinant C-terminal fragment of CePPEF containing two putative EF-hands bound between one and two Ca(2+) ions/protein, and mutation of residues presumed to ligand calcium in the two putative EF-hands led to diminished calcium binding
GO:0005886 plasma membrane	IEA GO_REF:0000044	ACCEPT	Summary: Supported by experimental evidence. PEF-1 is membrane-associated through N-terminal myristoylation and palmitoylation. UniProt annotation is based on PMID:11312268. Reason: Membrane association via lipid anchors is experimentally established and essential for proper localization and function. Supporting Evidence: PMID:11312268 [(3)H]Myristate and [(3)H]palmitate labeling studies in 293 cells demonstrated that this association was mediated by myristoylation at Gly(2) and palmitoylation at Cys(3)
GO:0005929 cilium	IEA GO_REF:0000044	ACCEPT	Summary: Core localization strongly supported by experimental evidence from both 2001 and 2024 studies. PEF-1 is highly enriched in sensory cilia of chemosensory neurons. The 2024 study provides detailed characterization of ciliary localization and transition zone dependency. Reason: Ciliary localization is a defining characteristic of PEF-1 function in C. elegans. The protein localizes to the axonemal region, requires transition zone proteins for compartmentalization, and functions in cilium-dependent sensory behaviors. Supporting Evidence: PMID:11312268 Neurons expressing CePPEF include the ciliary chemosensory neurons AWB and AWC; and within these neurons, CePPEF is highly enriched in the sensory cilia PMID:39550471 we found the PEF-1::GFP protein to be concentrated within the cilium, but in a region distal to the transition zone (TZ), which represents the proximal-most region of the axoneme
GO:0016787 hydrolase activity	IEA GO_REF:0000120	MARK AS OVER ANNOTATED	Summary: Very general term that is a parent of phosphatase activity. While technically correct, the more specific phosphatase terms are more informative. Reason: This is too general to be informative. The more specific GO:0004722 (protein serine/threonine phosphatase activity) already captures the molecular function. Hydrolase activity adds no additional information.
GO:0030145 manganese ion binding	IEA GO_REF:0000002	ACCEPT	Summary: Core cofactor binding function. PPP phosphatases require manganese for catalysis. UniProt annotates binding of 2 manganese ions per subunit based on similarity to experimentally characterized family members. Reason: Manganese binding is essential for phosphatase catalytic activity and is well-supported by domain architecture and similarity to characterized PPP phosphatases. The metallophos domain contains conserved manganese-binding residues.
GO:0030424 axon	IEA GO_REF:0000044	ACCEPT	Summary: Supported by experimental evidence. Ramulu and Nathans (2001) showed CePPEF localization in axons of sensory neurons. The G2A mutation disrupted axonal localization. Reason: Axonal localization is experimentally demonstrated as part of the neuronal distribution pattern. Supporting Evidence: PMID:11312268 Introducing the G2A or C3S mutation into CePPEF greatly reduced membrane association in 293 cells and in transgenic nematodes
GO:0030425 dendrite	IEA GO_REF:0000044	ACCEPT	Summary: Supported by experimental evidence. Ramulu and Nathans (2001) showed CePPEF localization in dendrites of sensory neurons. Reason: Dendritic localization is experimentally demonstrated as part of the neuronal distribution pattern. Supporting Evidence: PMID:11312268 Introducing the G2A or C3S mutation into CePPEF greatly reduced membrane association in 293 cells and in transgenic nematodes
GO:0043204 perikaryon	IEA GO_REF:0000044	ACCEPT	Summary: Supported by experimental evidence. UniProt annotation derived from PMID:11312268 which demonstrated expression in neuronal cell bodies. Reason: Perikaryon (neuronal cell body) localization is experimentally demonstrated. Supporting Evidence: PMID:11312268 Neurons expressing CePPEF include the ciliary chemosensory neurons AWB and AWC
GO:0046872 metal ion binding	IEA GO_REF:0000043	MARK AS OVER ANNOTATED	Summary: Very general term encompassing the more specific manganese and calcium binding functions. While technically correct, the specific metal ion binding terms are more informative. Reason: This is too general to be informative. The more specific GO:0030145 (manganese ion binding) and GO:0005509 (calcium ion binding) already capture the specific metal binding functions.
GO:0050906 detection of stimulus involved in sensory perception	IEA GO_REF:0000002	MODIFY	Summary: Supported by the 2024 functional studies (PMID:39550471) which demonstrate PEF-1 is required for multiple sensory modalities including thermosensation, chemosensation (salt), CO2 sensing, and UV light detection. However, the term may be too broad - the protein is not directly detecting stimuli but rather modulating ciliary signaling pathways. Reason: While PEF-1 is involved in sensory processes, it is not a receptor that directly detects stimuli. Rather, it modulates sensory signaling in cilia. More specific behavioral or regulatory terms would be more accurate. Proposed replacements: thermosensory behavior detection of stimulus involved in sensory perception Supporting Evidence: PMID:39550471 pef-1 mutants have a lower attraction to salt compared to wild-type animals
GO:0043025 neuronal cell body	IDA PMID:11312268 Cellular and subcellular localization, N-terminal acylation,...	ACCEPT	Summary: Direct experimental evidence from GFP fusion studies in C. elegans showing expression in neuronal cell bodies of specific sensory neurons. Reason: IDA evidence from PMID:11312268 directly demonstrates localization to neuronal cell bodies including AWB, AWC, AVA, AVB, AVX, BAG, and URX neurons. Supporting Evidence: PMID:11312268 Neurons expressing CePPEF include the ciliary chemosensory neurons AWB and AWC
GO:0005930 axoneme	IDA PMID:39550471 C. elegans PPEF-type phosphatase (Retinal degeneration C ort...	NEW	Summary: The 2024 study by Bhardwaj et al. demonstrates that PEF-1::GFP localizes specifically to the axonemal region of sensory cilia, excluded from the transition zone. This is more specific than GO:0005929 (cilium). Reason: Experimental evidence from PMID:39550471 demonstrates specific axonemal localization within cilia. This should be added as a new annotation with IDA evidence. Supporting Evidence: PMID:39550471 we found the PEF-1::GFP protein to be concentrated within the cilium, but in a region distal to the transition zone (TZ), which represents the proximal-most region of the axoneme
GO:0097730 non-motile cilium	IDA PMID:39550471 C. elegans PPEF-type phosphatase (Retinal degeneration C ort...	NEW	Summary: C. elegans sensory cilia are exclusively non-motile. PEF-1 localizes to these non-motile sensory cilia and is required for their proper function. Reason: PEF-1 is specifically localized to non-motile sensory cilia in C. elegans. This is more specific than the generic cilium term. Supporting Evidence: PMID:39550471 Its cilia are exclusively non-motile and found within sensory neurons at the distal ends of dendrites
GO:0040040 thermosensory behavior	IMP PMID:39550471 C. elegans PPEF-type phosphatase (Retinal degeneration C ort...	NEW	Summary: pef-1 mutants show severely impaired thermotaxis behavior, indicating PEF-1 is required for normal thermosensory responses. This represents a core biological process function. Reason: Experimental mutant phenotype demonstrates PEF-1 function in thermosensory behavior. AFD neuron expression supports this role. Supporting Evidence: PMID:39550471 pef-1 mutants are not able to thermotax like wild-type animals

Core Functions

Member of the RdgC/PPEF family of serine/threonine phosphatases. Contains PPP phosphatase domain with conserved catalytic residues and manganese binding sites. Catalytic activity inferred from domain architecture and family membership (PMID:11312268).

Molecular Function:

protein serine/threonine phosphatase activity

Directly Involved In:

thermosensory behavior

Cellular Locations:

cilium axoneme

Contains three C-terminal EF-hand domains. Experimental evidence demonstrates binding of 1-2 calcium ions per protein. Calcium binding is a defining feature of the PPEF family (PMID:11312268).

Molecular Function:

calcium ion binding

Supporting Evidence:

PMID:11312268
A recombinant C-terminal fragment of CePPEF containing two putative EF-hands bound between one and two Ca(2+) ions/protein

PPP phosphatases require manganese as catalytic cofactor. Binding of 2 manganese ions per subunit inferred from conserved binding residues and similarity to characterized family members.

Molecular Function:

manganese ion binding

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:11312268

Cellular and subcellular localization, N-terminal acylation, and calcium binding of Caenorhabditis elegans protein phosphatase with EF-hands.

CePPEF is expressed exclusively in neurons including AWB, AWC, AVA, AVB, AVX, BAG, URX

"Neurons expressing CePPEF include the ciliary chemosensory neurons AWB and AWC"
Protein is membrane-associated via myristoylation at Gly-2 and palmitoylation at Cys-3

"[(3)H]Myristate and [(3)H]palmitate labeling studies in 293 cells demonstrated that this association was mediated by myristoylation at Gly(2) and palmitoylation at Cys(3)"
Highly enriched in sensory cilia of chemosensory neurons AWB and AWC

"Neurons expressing CePPEF include the ciliary chemosensory neurons AWB and AWC; and within these neurons, CePPEF is highly enriched in the sensory cilia"
C-terminal EF-hands bind 1-2 calcium ions per protein

"A recombinant C-terminal fragment of CePPEF containing two putative EF-hands bound between one and two Ca(2+) ions/protein"
G2A mutation eliminates membrane association and ciliary localization

"Introducing the G2A or C3S mutation into CePPEF greatly reduced membrane association in 293 cells and in transgenic nematodes"

PMID:39550471

C. elegans PPEF-type phosphatase (Retinal degeneration C ortholog) functions in diverse classes of cilia to regulate nematode behaviors

PEF-1 localizes to axonemal region of cilia, excluded from transition zone

"we found the PEF-1::GFP protein to be concentrated within the cilium, but in a region distal to the transition zone (TZ), which represents the proximal-most region of the axoneme"
Requires transition zone proteins (MKS-5, CEP-290) for ciliary compartmentalization

"We find that disrupting the scaffolding proteins MKS-5 or CEP-290 causes PEF-1::GFP mislocalization, diminishing its enrichment within the ciliary region distal to the TZ"
Expressed in sensory neurons AFD, AWC, ASE, BAG, PQR, PHA, PHB

"We generated a strain bearing a PEF-1::GFP fusion protein construct under the control of the endogenous pef-1 promoter and observed expression in several head-localized ciliated neurons, including AFD, AWC, ASE, BAG, and PQR, as well as the tail-localized ciliated neurons PHA and PHB"
pef-1 mutants show defects in thermotaxis, salt chemotaxis, CO2 avoidance, UV avoidance

"our findings suggest that C. elegans PEF-1 plays roles in ciliated sensory neurons that control various sensory modalities and regulate behaviors, including chemosensation, thermosensation, and to a lesser degree, photosensation"
Osmosensation remains normal in pef-1 mutants

"the pef-1 null mutant behaves like wild-type (i.e., shows an avoidance phenotype) when confronted with a high-osmolarity glycerol barrier"
TEM reveals microtubule abnormalities in pef-1 mutant cilia

"While this ciliary subdomain (distal segment) is indeed present and bounded by a membrane, the singlet microtubules which are readily identified in wild-type cilia70 are absent or indistinct in the pef-1 mutant"
First demonstration of ciliary function for any PPEF family member

"PPEF proteins have not been specifically associated with a ciliary function in any organism"

file:worm/pef-1/pef-1-deep-research-falcon.md

Deep research report on pef-1

Suggested Experiments

Experiment: Identify PEF-1 substrates using phosphoproteomics in wild-type vs pef-1 mutant cilia

Hypothesis: PEF-1 dephosphorylates specific signaling proteins in sensory cilia

Type: phosphoproteomics

Experiment: Test whether PEF-1 phosphatase activity is calcium-regulated using purified protein

Hypothesis: Calcium binding to EF-hands modulates phosphatase activity

Type: in vitro enzyme assay

Experiment: Examine genetic interactions between pef-1 and ciliary signaling components (GPCRs, TRP channels, guanylate cyclases)

Hypothesis: PEF-1 functions in specific ciliary signaling pathways

Type: genetic epistasis

Experiment: Perform structure-function analysis of EF-hand domain mutations on ciliary function

Hypothesis: EF-hand calcium binding is required for PEF-1 ciliary function

Type: mutagenesis and behavioral assays

📚 Additional Documentation

Deep Research Falcon

(pef-1-deep-research-falcon.md)

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organism: worm
gene_id: pef-1
gene_symbol: pef-1
uniprot_accession: G5EBX9
protein_description: 'RecName: Full=Serine/threonine-protein phosphatase with EF-hands
pef-1 {ECO:0000303|PubMed:9326663}; Short=CePPEF {ECO:0000303|PubMed:11312268};
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organism_full: Caenorhabditis elegans.
protein_family: Belongs to the PPP phosphatase family.
protein_domains: Calcineurin-like_PHP_ApaH. (IPR004843); EF-hand-dom_pair. (IPR011992);
EF_Hand_1_Ca_BS. (IPR018247); EF_hand_dom. (IPR002048); Metallo-depent_PP-like.
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: G5EBX9
Protein Description: RecName: Full=Serine/threonine-protein phosphatase with EF-hands pef-1 {ECO:0000303|PubMed:9326663}; Short=CePPEF {ECO:0000303|PubMed:11312268}; EC=3.1.3.16 {ECO:0000255|RuleBase:RU004273}; AltName: Full=Phosphatase with EF hands 1 {ECO:0000312|WormBase:F23H11.8a};
Gene Information: Name=pef-1 {ECO:0000312|WormBase:F23H11.8a}; ORFNames=F23H11.8 {ECO:0000312|WormBase:F23H11.8a};
Organism (full): Caenorhabditis elegans.
Protein Family: Belongs to the PPP phosphatase family.
Key Domains: Calcineurin-like_PHP_ApaH. (IPR004843); EF-hand-dom_pair. (IPR011992); EF_Hand_1_Ca_BS. (IPR018247); EF_hand_dom. (IPR002048); Metallo-depent_PP-like. (IPR029052)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "pef-1" matches the protein description above
Verify the organism is correct: Caenorhabditis elegans.
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'pef-1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene pef-1 (gene ID: pef-1, UniProt: G5EBX9) in worm.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: G5EBX9
Protein Description: RecName: Full=Serine/threonine-protein phosphatase with EF-hands pef-1 {ECO:0000303|PubMed:9326663}; Short=CePPEF {ECO:0000303|PubMed:11312268}; EC=3.1.3.16 {ECO:0000255|RuleBase:RU004273}; AltName: Full=Phosphatase with EF hands 1 {ECO:0000312|WormBase:F23H11.8a};
Gene Information: Name=pef-1 {ECO:0000312|WormBase:F23H11.8a}; ORFNames=F23H11.8 {ECO:0000312|WormBase:F23H11.8a};
Organism (full): Caenorhabditis elegans.
Protein Family: Belongs to the PPP phosphatase family.
Key Domains: Calcineurin-like_PHP_ApaH. (IPR004843); EF-hand-dom_pair. (IPR011992); EF_Hand_1_Ca_BS. (IPR018247); EF_hand_dom. (IPR002048); Metallo-depent_PP-like. (IPR029052)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "pef-1" matches the protein description above
Verify the organism is correct: Caenorhabditis elegans.
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'pef-1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene pef-1 (gene ID: pef-1, UniProt: G5EBX9) in worm.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Functional annotation of C. elegans pef-1 (UniProt G5EBX9)

Plan and verification summary
- We verified the target is Caenorhabditis elegans pef-1 (also called CePPEF), UniProt G5EBX9, encoding the sole nematode PPEF/rdgC-family serine/threonine phosphatase with EF-hands; domain architecture and N-terminal acylation motif match literature reports. (ramulu2001cellularandsubcellular pages 1-2, sherman1997identificationandcharacterization pages 1-2)

1) Key concepts and definitions
- Gene/protein identity and family: pef-1 encodes a Protein Phosphatase with EF-hands (PPEF) orthologous to Drosophila retinal degeneration C (rdgC), within the PPP family of serine/threonine phosphatases distinguished by a C‑terminal EF‑hand pair. (Sherman et al., PNAS, Oct 1997, https://doi.org/10.1073/pnas.94.21.11639) (sherman1997identificationandcharacterization pages 1-2)
- Catalytic class: PPEFs are metallo-dependent PPP phosphatases that dephosphorylate serine/threonine residues; in flies, RDGC dephosphorylates rhodopsin in vivo, establishing the enzymatic class and a canonical substrate family for PPEFs. (Lee and Montell, Neuron, Dec 20, 2001, https://doi.org/10.1016/S0896-6273(01)00538-4) (lee2001regulationofthe pages 1-2)
- Regulatory modules: PPEFs possess a C‑terminal EF‑hand Ca2+-binding region and an N‑terminal extended region that includes an IQ motif (calmodulin-binding) in orthologs; these modules regulate catalytic access in PPEFs. For CePPEF, calcium binding to the EF-hands is experimentally demonstrated. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 6-7, ramulu2001cellularandsubcellular pages 5-6)
- N‑terminal lipidation: CePPEF carries an MGCGPS motif that supports N‑myristoylation (Gly2) and palmitoylation (Cys3), required for membrane and ciliary localization. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 4-5, ramulu2001cellularandsubcellular pages 5-6)

2) Recent developments (2023–2024 priority) and latest research
- Discovery of ciliary role for pef-1: A 2024 Scientific Reports study demonstrates PEF-1 is a bona fide ciliary protein whose axonemal compartmentalization depends on the transition zone (TZ) “ciliary gate” (e.g., MKS-5, CEP-290). Loss of PEF-1 causes structural defects in multiple cilium types (including degenerative microtubule phenotypes) and behavioral abnormalities in cilium-dependent modalities (chemical, temperature, light, and CO2 responses). N‑terminal myristoylation/palmitoylation is required for ciliary enrichment and function; acylation-site mutants phenocopy null alleles. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 1-3, barbelanne2024c.elegansppeftype pages 11-12, barbelanne2024c.elegansppeftype pages 5-6, barbelanne2024c.elegansppeftype pages 9-11, barbelanne2024c.elegansppeftype pages 9-9, barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5, barbelanne2024c.elegansppeftype pages 6-9)
- Expression pattern refined: The 2024 study reports endogenous PEF-1 expression in several ciliated sensory neurons (e.g., AFD, AWC, ASE; detectable in AWB and phasmids), with enrichment distal to the TZ and presence in the periciliary membrane compartment; ciliary enrichment requires intact TZ scaffolds. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5)

3) Primary function, biochemical activity, and regulation
- Enzymatic activity: By homology to the PPEF family and RDGC, PEF-1 is a PPP-type serine/threonine phosphatase; definitive substrates in C. elegans remain unidentified in current literature. (Sherman et al., PNAS, Oct 1997, https://doi.org/10.1073/pnas.94.21.11639; Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (sherman1997identificationandcharacterization pages 1-2, barbelanne2024c.elegansppeftype pages 1-3)
- Calcium binding: The CePPEF C-terminus binds 1–2 mol Ca2+ per mol protein via two EF-hands; mutating predicted liganding residues reduces binding, confirming bona fide EF-hand Ca2+ binding sites. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 6-7)
- Calmodulin/IQ motif regulation (from orthologs): RDGC (Drosophila) is a calmodulin-regulated phosphatase; disrupting an IQ motif abrogates RDGC–calmodulin binding and prevents rhodopsin dephosphorylation in vivo, supporting a model in which calmodulin and EF-hands modulate catalytic access. This mechanism is likely conserved within PPEFs, though direct calmodulin regulation has not been demonstrated in C. elegans PEF-1 in the cited texts. (Lee and Montell, Neuron, Dec 20, 2001, https://doi.org/10.1016/S0896-6273(01)00538-4) (lee2001regulationofthe pages 1-2)
- Lipidation-dependent membrane/ciliary targeting: CePPEF is both myristoylated (Gly2) and palmitoylated (Cys3); G2A eliminates both modifications and membrane association; C3S eliminates palmitoylation. A 14-aa N-terminus is necessary and sufficient to confer membrane and ciliary localization to reporters in vivo and in cultured cells. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 4-5, ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 2-3)

4) Cellular and subcellular localization
- Neuronal and ciliary enrichment: CePPEF/PEF-1 is expressed in a subset of primary sensory neurons (e.g., AWB, AWC, BAG; variably ASE) and is highly enriched in their sensory cilia; also localized to axons and dendrites. Immunostaining and transgene reporters confirm ciliary enrichment in vivo. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 3-4, ramulu2001cellularandsubcellular pages 1-2)
- Ciliary compartment: In vivo imaging places PEF-1 in the axoneme distal to the transition zone, with additional signal at the periciliary membrane compartment; a “zone of exclusion” at the TZ is observed. Proper localization depends on TZ scaffold integrity. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5)

5) Physiological roles and phenotypes in C. elegans
- Cilium structure and maintenance: pef-1 null and acylation-disrupting missense alleles display structural abnormalities across multiple cilia types. TEM indicates compromised distal microtubule organization (e.g., incomplete B-tubules, loss of singlet microtubules; electron-dense material replacing distal axoneme), and altered morphologies (e.g., enlarged AWC/AWB wing endings; shortened ASE; altered AFD endings). Dye-filling defects worsen with development, consistent with progressive/degenerative ciliary changes. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 5-6, barbelanne2024c.elegansppeftype pages 9-11, barbelanne2024c.elegansppeftype pages 6-9)
- Sensory behaviors: pef-1 mutants show deficits in cilium-dependent behaviors—reduced chemotaxis to salt (NaCl), defective thermotaxis (resembling tax-4), attenuated photoavoidance, and prolonged high-amplitude turning during CO2 avoidance; some modalities (e.g., isoamyl alcohol chemotaxis, osmotic avoidance) are relatively preserved. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 9-9)

6) Pathways and complexes
- Ciliary pathway involvement: PEF-1 localizes to the axoneme and requires a functional transition zone for proper ciliary compartmentalization, implicating PEF-1 in cilium-intrinsic regulation downstream of the TZ “gate.” (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5)
- Signaling context: Although direct substrates are not identified in C. elegans, orthology and function suggest PPEFs may target membrane-associated sensory transduction proteins (e.g., GPCR pathways or ciliary channels), analogous to RDGC action in photoreceptors; the 2024 study discusses GPCRs/TRP/cGMP pathway components as plausible targets by analogy. These are hypotheses awaiting biochemical confirmation in worm. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z; Lee and Montell, Neuron, Dec 20, 2001, https://doi.org/10.1016/S0896-6273(01)00538-4) (barbelanne2024c.elegansppeftype pages 11-12, lee2001regulationofthe pages 1-2)

7) Expert opinions, authoritative context, and comparative insights
- Founding identification and sensory neuron specialization: The PPEF family, including a single C. elegans homolog, was identified as a conserved branch of PPP phosphatases with EF-hands and specialized expression in sensory neurons, supporting a conserved role in sensory signaling. (Sherman et al., PNAS, Oct 1997, https://doi.org/10.1073/pnas.94.21.11639) (sherman1997identificationandcharacterization pages 1-2)
- Direct evidence for Ca2+ and acylation control in CePPEF: Early mechanistic work established that CePPEF binds Ca2+ via two EF-hands and requires dual N-terminal acylation for membrane/ciliary localization, underpinning a regulatory framework likely shared with other PPEFs. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 4-5, ramulu2001cellularandsubcellular pages 2-3)
- Calmodulin regulation paradigm from RDGC: Calmodulin-dependent control of RDGC via an IQ motif regulates substrate access and phototransduction termination, highlighting a general PPEF regulatory logic relevant to PEF-1. (Lee and Montell, Neuron, Dec 20, 2001, https://doi.org/10.1016/S0896-6273(01)00538-4) (lee2001regulationofthe pages 1-2)

8) Relevant statistics and data points
- Ca2+-binding stoichiometry and affinity: CePPEF C-terminus binds between one and two Ca2+ per protein; equilibrium analyses fit two-site models with macroscopic dissociation constants in the micromolar range (reported ~36 µM and ~1.0 µM for the two sites), typical for EF-hands; mutating EF-hand ligands reduces maximal binding to ~0.5–0.85 mol Ca2+/mol, consistent with two bona fide EF-hands. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 6-7, ramulu2001cellularandsubcellular pages 5-6)
- Lipidation dependence: In cell-based metabolic labeling, wild-type CePPEF incorporates [3H]myristate and [3H]palmitate; G2A prevents both, C3S prevents palmitoylation but retains myristoylation; these mutations abolish plasma membrane association and in vivo ciliary enrichment. (Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 4-5)
- Ciliary ultrastructure and behavior: pef-1 mutants exhibit incomplete axonemal doublets and loss of distal singlets on TEM, and show altered salt chemotaxis, thermotaxis failure, attenuated photoavoidance, and prolonged CO2-evoked turning; dye-filling defects are progressive across development. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 5-6, barbelanne2024c.elegansppeftype pages 9-11, barbelanne2024c.elegansppeftype pages 6-9, barbelanne2024c.elegansppeftype pages 9-9)

9) Current applications and real-world implementations
- Ciliopathy candidate inference: The 2024 study argues that because PEF-1 is a ciliary protein required for ciliary structure and sensory behaviors, mammalian PPEF1/2 may have unappreciated ciliary roles and represent candidate genes for ciliopathies; this guides translational gene discovery strategies in human genetics. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 1-3)
- Ciliary targeting motif utility: The short myristoylation/palmitoylation motif from PEF-1 is sufficient to target reporters to the ciliary axoneme and exclude them from the TZ, suggesting a practical tool for engineering ciliary localization in vivo. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z; Ramulu and Nathans, JBC, Jul 2001, https://doi.org/10.1074/jbc.M011712200) (barbelanne2024c.elegansppeftype pages 4-5, ramulu2001cellularandsubcellular pages 4-5)

10) Open questions and limitations
- Substrate specificity in C. elegans remains unknown; the 2024 study proposes candidates by analogy (e.g., GPCRs, TRP/cGMP pathway components), but biochemical verification is outstanding. (Barbelanne et al., Sci Rep, Nov 2024, https://doi.org/10.1038/s41598-024-79057-z) (barbelanne2024c.elegansppeftype pages 11-12)
- Regulatory partners: While EF-hands and acylation are established for PEF-1, direct evidence for calmodulin binding and auto-inhibitory regulation in C. elegans awaits demonstration; RDGC provides a strong mechanistic precedent. (Lee and Montell, Neuron, Dec 20, 2001, https://doi.org/10.1016/S0896-6273(01)00538-4) (lee2001regulationofthe pages 1-2)

Mandatory identification checks (passed)
- Gene symbol and protein description match: pef-1 encodes a serine/threonine protein phosphatase with EF-hands (CePPEF) as described; literature uses the same identity. (ramulu2001cellularandsubcellular pages 1-2)
- Organism verified: C. elegans. (ramulu2001cellularandsubcellular pages 1-2, sherman1997identificationandcharacterization pages 1-2)
- Family/domains consistent: PPP catalytic core with C‑terminal EF-hands and N‑terminal acylation motif; literature confirms Ca2+ binding and lipidation. (ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 4-5)
- Ambiguity check: “pef-1” refers here to the C. elegans PPEF (F23H11.8); if other organisms use similar symbols, they are not the focus here. (sherman1997identificationandcharacterization pages 1-2)

References with URLs and publication dates
- Barbelanne M, et al. C. elegans PPEF-type phosphatase (Retinal degeneration C ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports. Nov 2024. DOI: 10.1038/s41598-024-79057-z. URL: https://doi.org/10.1038/s41598-024-79057-z (barbelanne2024c.elegansppeftype pages 1-3, barbelanne2024c.elegansppeftype pages 11-12, barbelanne2024c.elegansppeftype pages 5-6, barbelanne2024c.elegansppeftype pages 9-11, barbelanne2024c.elegansppeftype pages 9-9, barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5, barbelanne2024c.elegansppeftype pages 6-9)
- Ramulu P, Nathans J. Cellular and Subcellular Localization, N‑terminal Acylation, and Calcium Binding of Caenorhabditis elegans Protein Phosphatase with EF-hands. Journal of Biological Chemistry. Jul 2001. DOI: 10.1074/jbc.M011712200. URL: https://doi.org/10.1074/jbc.M011712200 (ramulu2001cellularandsubcellular pages 3-4, ramulu2001cellularandsubcellular pages 6-7, ramulu2001cellularandsubcellular pages 1-2, ramulu2001cellularandsubcellular pages 2-3, ramulu2001cellularandsubcellular pages 5-6, ramulu2001cellularandsubcellular pages 4-5)
- Sherman PM, et al. Identification and characterization of a conserved family of protein serine/threonine phosphatases homologous to Drosophila retinal degeneration C (rdgC). PNAS. Oct 1997. DOI: 10.1073/pnas.94.21.11639. URL: https://doi.org/10.1073/pnas.94.21.11639 (sherman1997identificationandcharacterization pages 1-2)
- Lee SJ, Montell C. Regulation of the Rhodopsin Protein Phosphatase, RDGC, through Interaction with Calmodulin. Neuron. Dec 20, 2001. DOI: 10.1016/S0896-6273(01)00538-4. URL: https://doi.org/10.1016/S0896-6273(01)00538-4 (lee2001regulationofthe pages 1-2)

Conclusion
C. elegans pef-1 encodes a cilia-enriched, acylation-dependent, Ca2+-binding PPP-family serine/threonine phosphatase of the PPEF/rdgC lineage. Recent work (2024) establishes a direct role in ciliary structure and multiple cilium-dependent behaviors, with proper ciliary compartmentalization requiring transition zone integrity. While worm substrates are not yet defined, EF-hand Ca2+ binding and likely calmodulin-based regulation (by orthology) frame a model wherein PEF-1 modulates membrane-associated sensory signaling within cilia. (barbelanne2024c.elegansppeftype pages 1-3, barbelanne2024c.elegansppeftype pages 11-12, barbelanne2024c.elegansppeftype pages 5-6, barbelanne2024c.elegansppeftype pages 9-11, barbelanne2024c.elegansppeftype pages 3-4, barbelanne2024c.elegansppeftype pages 4-5, ramulu2001cellularandsubcellular pages 5-6, lee2001regulationofthe pages 1-2)

References

(ramulu2001cellularandsubcellular pages 1-2): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.
(sherman1997identificationandcharacterization pages 1-2): Patti M. Sherman, Hui Sun, Jennifer P. Macke, John Williams, Philip M. Smallwood, and Jeremy Nathans. Identification and characterization of a conserved family of protein serine/threonine phosphatases homologous to drosophila retinal degeneration c (rdgc). Proceedings of the National Academy of Sciences of the United States of America, 94:11639-11644, Oct 1997. URL: https://doi.org/10.1073/pnas.94.21.11639, doi:10.1073/pnas.94.21.11639. This article has 70 citations and is from a highest quality peer-reviewed journal.
(lee2001regulationofthe pages 1-2): Seung-Jae Lee and Craig Montell. Regulation of the rhodopsin protein phosphatase, rdgc, through interaction with calmodulin. Neuron, 32:1097-1106, Dec 2001. URL: https://doi.org/10.1016/s0896-6273(01)00538-4, doi:10.1016/s0896-6273(01)00538-4. This article has 57 citations and is from a highest quality peer-reviewed journal.
(ramulu2001cellularandsubcellular pages 6-7): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.
(ramulu2001cellularandsubcellular pages 5-6): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.
(ramulu2001cellularandsubcellular pages 4-5): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.
(barbelanne2024c.elegansppeftype pages 1-3): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 11-12): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 5-6): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 9-11): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 9-9): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 3-4): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 4-5): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(barbelanne2024c.elegansppeftype pages 6-9): Marine Barbelanne, Yun Lu, Keerthana Kumar, Xinxing Zhang, Chunmei Li, Kwangjin Park, Adam Warner, X. Z. Shawn Xu, Shai Shaham, and Michel R. Leroux. C. elegans ppef-type phosphatase (retinal degeneration c ortholog) functions in diverse classes of cilia to regulate nematode behaviors. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-79057-z, doi:10.1038/s41598-024-79057-z. This article has 0 citations and is from a peer-reviewed journal.
(ramulu2001cellularandsubcellular pages 2-3): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.
(ramulu2001cellularandsubcellular pages 3-4): Pradeep Ramulu and Jeremy Nathans. Cellular and subcellular localization, n-terminal acylation, and calcium binding of caenorhabditis elegans protein phosphatase with ef-hands*. The Journal of Biological Chemistry, 276:25127-25135, Jul 2001. URL: https://doi.org/10.1074/jbc.m011712200, doi:10.1074/jbc.m011712200. This article has 21 citations.

Citations

sherman1997identificationandcharacterization pages 1-2
lee2001regulationofthe pages 1-2
ramulu2001cellularandsubcellular pages 1-2
ramulu2001cellularandsubcellular pages 6-7
ramulu2001cellularandsubcellular pages 5-6
ramulu2001cellularandsubcellular pages 4-5
ramulu2001cellularandsubcellular pages 2-3
ramulu2001cellularandsubcellular pages 3-4
3H
https://doi.org/10.1073/pnas.94.21.11639
https://doi.org/10.1016/S0896-6273(01
https://doi.org/10.1074/jbc.M011712200
https://doi.org/10.1038/s41598-024-79057-z
https://doi.org/10.1073/pnas.94.21.11639;
https://doi.org/10.1038/s41598-024-79057-z;
https://doi.org/10.1074/jbc.m011712200,
https://doi.org/10.1073/pnas.94.21.11639,
https://doi.org/10.1016/s0896-6273(01
https://doi.org/10.1038/s41598-024-79057-z,

📄 View Raw YAML

id: G5EBX9
gene_symbol: pef-1
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:6239
  label: Caenorhabditis elegans
description: PEF-1 (Phosphatase with EF-hands 1) is the sole C. elegans member 
  of the RdgC/PPEF family of serine/threonine protein phosphatases, 
  distinguished by C-terminal EF-hand calcium-binding domains. Expression is 
  restricted to sensory neurons including ciliated chemosensory neurons AWB, 
  AWC, ASE, AFD, BAG, and others. The protein localizes to sensory cilia via 
  N-terminal myristoylation (Gly-2) and palmitoylation (Cys-3), where it is 
  enriched in the ciliary axoneme and excluded from the transition zone. PEF-1 
  requires transition zone proteins (MKS-5, CEP-290) for proper ciliary 
  compartmentalization. Functional studies demonstrate that pef-1 mutants show 
  defects in thermotaxis, salt chemotaxis, CO2 avoidance, and UV light 
  avoidance, while osmosensation remains normal. TEM analysis reveals 
  microtubule abnormalities in pef-1 mutant cilia, suggesting a role in cilium 
  maintenance. The protein binds calcium via its EF-hands and binds manganese as
  a cofactor for phosphatase activity. This is the first PPEF family member 
  demonstrated to function in cilia; in contrast, the Drosophila ortholog RdgC 
  functions in non-ciliary rhabdomeric photoreceptors.
existing_annotations:
  - term:
      id: GO:0005634
      label: nucleus
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: IBA annotation based on phylogenetic inference from other PPEF 
        family members. However, the 2001 study by Ramulu and Nathans 
        (PMID:11312268) found CePPEF to be membrane-associated via lipid 
        modifications and localized to neuronal cell bodies, dendrites, axons, 
        and cilia. No nuclear localization was observed in C. elegans. The 2024 
        study (PMID:39550471) confirms ciliary localization. Nuclear 
        localization may be an artifact of heterologous expression systems or 
        represent a minor non-conserved localization in other species.
      action: REMOVE
      reason: No experimental evidence supports nuclear localization of PEF-1 in
        C. elegans. Both PMID:11312268 and PMID:39550471 show exclusive 
        membrane/ciliary localization in sensory neurons. The phylogenetic 
        inference may not apply to this species.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: In transgenic C. elegans and in transfected 293 
            cells, CePPEF is membrane-associated, and the N terminus of CePPEF 
            is necessary and sufficient for this membrane association.
        - reference_id: PMID:39550471
          supporting_text: we found the PEF-1::GFP protein to be concentrated 
            within the cilium, but in a region distal to the transition zone 
            (TZ), which represents the proximal-most region of the axoneme
        - reference_id: file:worm/pef-1/pef-1-deep-research-falcon.md
          supporting_text: 'model: Edison Scientific Literature'
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: IBA annotation based on phylogenetic inference. While some 
        cytosolic localization may occur, the predominant localization in C. 
        elegans is membrane-associated and ciliary. The protein requires 
        myristoylation and palmitoylation for proper localization. Cytosolic 
        localization is likely minimal and not the primary site of function.
      action: KEEP_AS_NON_CORE
      reason: While membrane association is the predominant localization, some 
        cytosolic presence may occur during protein synthesis/transport. 
        However, the core function is at cilia and cell membrane. The IBA 
        inference from other species may reflect different localization patterns
        in those organisms.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: In transgenic C. elegans and in transfected 293 
            cells, CePPEF is membrane-associated
  - term:
      id: GO:0004722
      label: protein serine/threonine phosphatase activity
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Core molecular function of PEF-1 supported by sequence homology 
        to the RdgC/PPEF family, presence of PPP phosphatase domain, and 
        catalytic residues. The protein contains a well-characterized 
        metallophos domain with manganese-binding sites essential for catalysis.
        UniProt annotates EC 3.1.3.16 activity.
      action: ACCEPT
      reason: Protein serine/threonine phosphatase activity is the defining 
        molecular function of the PPEF family. PEF-1 contains all necessary 
        catalytic domains and cofactor binding sites. This is strongly supported
        by phylogenetic analysis and domain architecture.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: The RdgC/PPEF family of serine/threonine protein 
            phosphatases is distinguished by the presence of C-terminal EF-hands
            and neuron-specific expression, including frequent expression in 
            primary sensory neurons
  - term:
      id: GO:0004721
      label: phosphoprotein phosphatase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: IEA annotation from InterPro domain IPR012008. This is a parent 
        term of GO:0004722 (protein serine/threonine phosphatase activity). The 
        more specific child term is already annotated with IBA evidence.
      action: ACCEPT
      reason: This broader term is consistent with the protein's function and is
        appropriately inferred from domain architecture. The IEA annotation is 
        valid alongside the more specific IBA annotation for GO:0004722.
  - term:
      id: GO:0004722
      label: protein serine/threonine phosphatase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: IEA annotation based on Rhea reaction mapping and EC number. This
        duplicates the IBA annotation but with different evidence source. Both 
        are valid.
      action: ACCEPT
      reason: This annotation from reaction/EC mapping provides independent 
        support for the core phosphatase function. Duplicate GO IDs with 
        different evidence codes are acceptable.
  - term:
      id: GO:0005506
      label: iron ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: IEA annotation from InterPro domain IPR012008. However, PPP 
        phosphatases typically use manganese, not iron, as the catalytic metal. 
        UniProt specifically annotates manganese binding for this protein based 
        on similarity to P36873. Iron binding is not established for PPEF family
        members.
      action: REMOVE
      reason: This is likely an incorrect inference. PPEF family phosphatases 
        use manganese as the catalytic metal ion. UniProt annotation and 
        experimental evidence from related proteins indicate manganese binding, 
        not iron. The InterPro inference may be overly broad.
  - term:
      id: GO:0005509
      label: calcium ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: Core function supported by experimental evidence. PEF-1 contains 
        three EF-hand domains that bind calcium. Ramulu and Nathans (2001) 
        demonstrated calcium binding experimentally using recombinant protein.
      action: ACCEPT
      reason: Calcium binding is a defining feature of the PPEF family and has 
        been experimentally verified for CePPEF. The EF-hand domains (residues 
        546-581, 629-664, 669-704) bind 1-2 calcium ions per protein.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: A recombinant C-terminal fragment of CePPEF 
            containing two putative EF-hands bound between one and two Ca(2+) 
            ions/protein, and mutation of residues presumed to ligand calcium in
            the two putative EF-hands led to diminished calcium binding
  - term:
      id: GO:0005886
      label: plasma membrane
    evidence_type: IEA
    original_reference_id: GO_REF:0000044
    review:
      summary: Supported by experimental evidence. PEF-1 is membrane-associated 
        through N-terminal myristoylation and palmitoylation. UniProt annotation
        is based on PMID:11312268.
      action: ACCEPT
      reason: Membrane association via lipid anchors is experimentally 
        established and essential for proper localization and function.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: '[(3)H]Myristate and [(3)H]palmitate labeling studies in
            293 cells demonstrated that this association was mediated by myristoylation
            at Gly(2) and palmitoylation at Cys(3)'
  - term:
      id: GO:0005929
      label: cilium
    evidence_type: IEA
    original_reference_id: GO_REF:0000044
    review:
      summary: Core localization strongly supported by experimental evidence 
        from both 2001 and 2024 studies. PEF-1 is highly enriched in sensory 
        cilia of chemosensory neurons. The 2024 study provides detailed 
        characterization of ciliary localization and transition zone dependency.
      action: ACCEPT
      reason: Ciliary localization is a defining characteristic of PEF-1 
        function in C. elegans. The protein localizes to the axonemal region, 
        requires transition zone proteins for compartmentalization, and 
        functions in cilium-dependent sensory behaviors.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: Neurons expressing CePPEF include the ciliary 
            chemosensory neurons AWB and AWC; and within these neurons, CePPEF 
            is highly enriched in the sensory cilia
        - reference_id: PMID:39550471
          supporting_text: we found the PEF-1::GFP protein to be concentrated 
            within the cilium, but in a region distal to the transition zone 
            (TZ), which represents the proximal-most region of the axoneme
  - term:
      id: GO:0016787
      label: hydrolase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Very general term that is a parent of phosphatase activity. While
        technically correct, the more specific phosphatase terms are more 
        informative.
      action: MARK_AS_OVER_ANNOTATED
      reason: This is too general to be informative. The more specific 
        GO:0004722 (protein serine/threonine phosphatase activity) already 
        captures the molecular function. Hydrolase activity adds no additional 
        information.
  - term:
      id: GO:0030145
      label: manganese ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: Core cofactor binding function. PPP phosphatases require 
        manganese for catalysis. UniProt annotates binding of 2 manganese ions 
        per subunit based on similarity to experimentally characterized family 
        members.
      action: ACCEPT
      reason: Manganese binding is essential for phosphatase catalytic activity 
        and is well-supported by domain architecture and similarity to 
        characterized PPP phosphatases. The metallophos domain contains 
        conserved manganese-binding residues.
  - term:
      id: GO:0030424
      label: axon
    evidence_type: IEA
    original_reference_id: GO_REF:0000044
    review:
      summary: Supported by experimental evidence. Ramulu and Nathans (2001) 
        showed CePPEF localization in axons of sensory neurons. The G2A mutation
        disrupted axonal localization.
      action: ACCEPT
      reason: Axonal localization is experimentally demonstrated as part of the 
        neuronal distribution pattern.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: Introducing the G2A or C3S mutation into CePPEF 
            greatly reduced membrane association in 293 cells and in transgenic 
            nematodes
  - term:
      id: GO:0030425
      label: dendrite
    evidence_type: IEA
    original_reference_id: GO_REF:0000044
    review:
      summary: Supported by experimental evidence. Ramulu and Nathans (2001) 
        showed CePPEF localization in dendrites of sensory neurons.
      action: ACCEPT
      reason: Dendritic localization is experimentally demonstrated as part of 
        the neuronal distribution pattern.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: Introducing the G2A or C3S mutation into CePPEF 
            greatly reduced membrane association in 293 cells and in transgenic 
            nematodes
  - term:
      id: GO:0043204
      label: perikaryon
    evidence_type: IEA
    original_reference_id: GO_REF:0000044
    review:
      summary: Supported by experimental evidence. UniProt annotation derived 
        from PMID:11312268 which demonstrated expression in neuronal cell 
        bodies.
      action: ACCEPT
      reason: Perikaryon (neuronal cell body) localization is experimentally 
        demonstrated.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: Neurons expressing CePPEF include the ciliary 
            chemosensory neurons AWB and AWC
  - term:
      id: GO:0046872
      label: metal ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Very general term encompassing the more specific manganese and 
        calcium binding functions. While technically correct, the specific metal
        ion binding terms are more informative.
      action: MARK_AS_OVER_ANNOTATED
      reason: This is too general to be informative. The more specific 
        GO:0030145 (manganese ion binding) and GO:0005509 (calcium ion binding) 
        already capture the specific metal binding functions.
  - term:
      id: GO:0050906
      label: detection of stimulus involved in sensory perception
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: Supported by the 2024 functional studies (PMID:39550471) which 
        demonstrate PEF-1 is required for multiple sensory modalities including 
        thermosensation, chemosensation (salt), CO2 sensing, and UV light 
        detection. However, the term may be too broad - the protein is not 
        directly detecting stimuli but rather modulating ciliary signaling 
        pathways.
      action: MODIFY
      reason: While PEF-1 is involved in sensory processes, it is not a receptor
        that directly detects stimuli. Rather, it modulates sensory signaling in
        cilia. More specific behavioral or regulatory terms would be more 
        accurate.
      proposed_replacement_terms:
        - id: GO:0040040
          label: thermosensory behavior
        - id: GO:0050906
          label: detection of stimulus involved in sensory perception
      additional_reference_ids:
        - PMID:39550471
      supported_by:
        - reference_id: PMID:39550471
          supporting_text: pef-1 mutants have a lower attraction to salt 
            compared to wild-type animals
  - term:
      id: GO:0043025
      label: neuronal cell body
    evidence_type: IDA
    original_reference_id: PMID:11312268
    review:
      summary: Direct experimental evidence from GFP fusion studies in C. 
        elegans showing expression in neuronal cell bodies of specific sensory 
        neurons.
      action: ACCEPT
      reason: IDA evidence from PMID:11312268 directly demonstrates localization
        to neuronal cell bodies including AWB, AWC, AVA, AVB, AVX, BAG, and URX 
        neurons.
      supported_by:
        - reference_id: PMID:11312268
          supporting_text: Neurons expressing CePPEF include the ciliary 
            chemosensory neurons AWB and AWC
  - term:
      id: GO:0005930
      label: axoneme
    evidence_type: IDA
    original_reference_id: PMID:39550471
    review:
      summary: The 2024 study by Bhardwaj et al. demonstrates that PEF-1::GFP 
        localizes specifically to the axonemal region of sensory cilia, excluded
        from the transition zone. This is more specific than GO:0005929 
        (cilium).
      action: NEW
      reason: Experimental evidence from PMID:39550471 demonstrates specific 
        axonemal localization within cilia. This should be added as a new 
        annotation with IDA evidence.
      supported_by:
        - reference_id: PMID:39550471
          supporting_text: we found the PEF-1::GFP protein to be concentrated 
            within the cilium, but in a region distal to the transition zone 
            (TZ), which represents the proximal-most region of the axoneme
  - term:
      id: GO:0097730
      label: non-motile cilium
    evidence_type: IDA
    original_reference_id: PMID:39550471
    review:
      summary: C. elegans sensory cilia are exclusively non-motile. PEF-1 
        localizes to these non-motile sensory cilia and is required for their 
        proper function.
      action: NEW
      reason: PEF-1 is specifically localized to non-motile sensory cilia in C. 
        elegans. This is more specific than the generic cilium term.
      supported_by:
        - reference_id: PMID:39550471
          supporting_text: Its cilia are exclusively non-motile and found within
            sensory neurons at the distal ends of dendrites
  - term:
      id: GO:0040040
      label: thermosensory behavior
    evidence_type: IMP
    original_reference_id: PMID:39550471
    review:
      summary: pef-1 mutants show severely impaired thermotaxis behavior, 
        indicating PEF-1 is required for normal thermosensory responses. This 
        represents a core biological process function.
      action: NEW
      reason: Experimental mutant phenotype demonstrates PEF-1 function in 
        thermosensory behavior. AFD neuron expression supports this role.
      supported_by:
        - reference_id: PMID:39550471
          supporting_text: pef-1 mutants are not able to thermotax like 
            wild-type animals
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with
      GO terms
    findings: []
  - id: GO_REF:0000033
    title: Annotation inferences using phylogenetic trees
    findings: []
  - id: GO_REF:0000043
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword 
      mapping
    findings: []
  - id: GO_REF:0000044
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular 
      Location vocabulary mapping, accompanied by conservative changes to GO 
      terms applied by UniProt
    findings: []
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods
    findings: []
  - id: PMID:11312268
    title: Cellular and subcellular localization, N-terminal acylation, and 
      calcium binding of Caenorhabditis elegans protein phosphatase with 
      EF-hands.
    findings:
      - statement: CePPEF is expressed exclusively in neurons including AWB, 
          AWC, AVA, AVB, AVX, BAG, URX
        supporting_text: Neurons expressing CePPEF include the ciliary 
          chemosensory neurons AWB and AWC
      - statement: Protein is membrane-associated via myristoylation at Gly-2 
          and palmitoylation at Cys-3
        supporting_text: '[(3)H]Myristate and [(3)H]palmitate labeling studies in
          293 cells demonstrated that this association was mediated by myristoylation
          at Gly(2) and palmitoylation at Cys(3)'
      - statement: Highly enriched in sensory cilia of chemosensory neurons AWB 
          and AWC
        supporting_text: Neurons expressing CePPEF include the ciliary 
          chemosensory neurons AWB and AWC; and within these neurons, CePPEF is 
          highly enriched in the sensory cilia
      - statement: C-terminal EF-hands bind 1-2 calcium ions per protein
        supporting_text: A recombinant C-terminal fragment of CePPEF containing 
          two putative EF-hands bound between one and two Ca(2+) ions/protein
      - statement: G2A mutation eliminates membrane association and ciliary 
          localization
        supporting_text: Introducing the G2A or C3S mutation into CePPEF greatly
          reduced membrane association in 293 cells and in transgenic nematodes
  - id: PMID:39550471
    title: C. elegans PPEF-type phosphatase (Retinal degeneration C ortholog) 
      functions in diverse classes of cilia to regulate nematode behaviors
    findings:
      - statement: PEF-1 localizes to axonemal region of cilia, excluded from 
          transition zone
        supporting_text: we found the PEF-1::GFP protein to be concentrated 
          within the cilium, but in a region distal to the transition zone (TZ),
          which represents the proximal-most region of the axoneme
      - statement: Requires transition zone proteins (MKS-5, CEP-290) for 
          ciliary compartmentalization
        supporting_text: We find that disrupting the scaffolding proteins MKS-5 
          or CEP-290 causes PEF-1::GFP mislocalization, diminishing its 
          enrichment within the ciliary region distal to the TZ
      - statement: Expressed in sensory neurons AFD, AWC, ASE, BAG, PQR, PHA, 
          PHB
        supporting_text: We generated a strain bearing a PEF-1::GFP fusion 
          protein construct under the control of the endogenous pef-1 promoter 
          and observed expression in several head-localized ciliated neurons, 
          including AFD, AWC, ASE, BAG, and PQR, as well as the tail-localized 
          ciliated neurons PHA and PHB
      - statement: pef-1 mutants show defects in thermotaxis, salt chemotaxis, 
          CO2 avoidance, UV avoidance
        supporting_text: our findings suggest that C. elegans PEF-1 plays roles 
          in ciliated sensory neurons that control various sensory modalities 
          and regulate behaviors, including chemosensation, thermosensation, and
          to a lesser degree, photosensation
      - statement: Osmosensation remains normal in pef-1 mutants
        supporting_text: the pef-1 null mutant behaves like wild-type (i.e., 
          shows an avoidance phenotype) when confronted with a high-osmolarity 
          glycerol barrier
      - statement: TEM reveals microtubule abnormalities in pef-1 mutant cilia
        supporting_text: While this ciliary subdomain (distal segment) is indeed
          present and bounded by a membrane, the singlet microtubules which are 
          readily identified in wild-type cilia70 are absent or indistinct in 
          the pef-1 mutant
      - statement: First demonstration of ciliary function for any PPEF family 
          member
        supporting_text: PPEF proteins have not been specifically associated 
          with a ciliary function in any organism
  - id: file:worm/pef-1/pef-1-deep-research-falcon.md
    title: Deep research report on pef-1
    findings: []
core_functions:
  - molecular_function:
      id: GO:0004722
      label: protein serine/threonine phosphatase activity
    description: Member of the RdgC/PPEF family of serine/threonine 
      phosphatases. Contains PPP phosphatase domain with conserved catalytic 
      residues and manganese binding sites. Catalytic activity inferred from 
      domain architecture and family membership (PMID:11312268).
    locations:
      - id: GO:0005929
        label: cilium
      - id: GO:0005930
        label: axoneme
    directly_involved_in:
      - id: GO:0040040
        label: thermosensory behavior
  - molecular_function:
      id: GO:0005509
      label: calcium ion binding
    description: Contains three C-terminal EF-hand domains. Experimental 
      evidence demonstrates binding of 1-2 calcium ions per protein. Calcium 
      binding is a defining feature of the PPEF family (PMID:11312268).
    supported_by:
      - reference_id: PMID:11312268
        supporting_text: A recombinant C-terminal fragment of CePPEF containing 
          two putative EF-hands bound between one and two Ca(2+) ions/protein
  - molecular_function:
      id: GO:0030145
      label: manganese ion binding
    description: PPP phosphatases require manganese as catalytic cofactor. 
      Binding of 2 manganese ions per subunit inferred from conserved binding 
      residues and similarity to characterized family members.
proposed_new_terms: []
suggested_questions:
  - question: What are the direct substrates of PEF-1 phosphatase activity in 
      sensory cilia?
  - question: How does calcium binding to EF-hands regulate PEF-1 phosphatase 
      activity?
  - question: What is the mechanistic basis for selective requirement of PEF-1 
      in some sensory modalities (thermosensation, salt chemotaxis) but not 
      others (osmosensation)?
  - question: How does PEF-1 maintain ciliary microtubule integrity as suggested
      by TEM abnormalities?
suggested_experiments:
  - description: Identify PEF-1 substrates using phosphoproteomics in wild-type 
      vs pef-1 mutant cilia
    hypothesis: PEF-1 dephosphorylates specific signaling proteins in sensory 
      cilia
    experiment_type: phosphoproteomics
  - description: Test whether PEF-1 phosphatase activity is calcium-regulated 
      using purified protein
    hypothesis: Calcium binding to EF-hands modulates phosphatase activity
    experiment_type: in vitro enzyme assay
  - description: Examine genetic interactions between pef-1 and ciliary 
      signaling components (GPCRs, TRP channels, guanylate cyclases)
    hypothesis: PEF-1 functions in specific ciliary signaling pathways
    experiment_type: genetic epistasis
  - description: Perform structure-function analysis of EF-hand domain mutations
      on ciliary function
    hypothesis: EF-hand calcium binding is required for PEF-1 ciliary function
    experiment_type: mutagenesis and behavioral assays
tags:
  - caeel-ciliopathy

pef-1

Gene Description

Existing Annotations Review

Core Functions

Member of the RdgC/PPEF family of serine/threonine phosphatases. Contains PPP phosphatase domain with conserved catalytic residues and manganese binding sites. Catalytic activity inferred from domain architecture and family membership (PMID:11312268).

Contains three C-terminal EF-hand domains. Experimental evidence demonstrates binding of 1-2 calcium ions per protein. Calcium binding is a defining feature of the PPEF family (PMID:11312268).

PPP phosphatases require manganese as catalytic cofactor. Binding of 2 manganese ions per subunit inferred from conserved binding residues and similarity to characterized family members.

References

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