F4JLB7 is a 450-residue leucine-rich-repeat receptor-like protein (RLP) encoded by the Arabidopsis thaliana At4g28560 locus. It has an N-terminal signal peptide, an extracellular LRR solenoid, and a C-terminal hydrophobic segment with almost no cytoplasmic tail. That segment could be a single-pass anchor or a GPI-attachment signal. The protein has no protein kinase domain and no CRIB motif. In the PANTHER PTHR48004 tree it is sister to the clade containing TOO MANY MOUTHS (TMM) and RLP29, within a family of noncatalytic cell-surface LRR receptor-like proteins that includes CLAVATA2. Like its relatives it is expected at the plasma membrane and to act in receptor-mediated signaling, but its ligand, receptor-kinase partners and biological role are unknown. Despite sharing the TAIR symbol RIC7, it is not the CRIB-motif ROP effector RIC7, which is encoded by the adjacent locus At4g28556.
Summary: PAINT places plasma-membrane localization at the root node of PTHR48004 (PTN008274137), with CLV2, TMM, PII-2 and AT4G28560 as seeds. F4JLB7 is inside that family, and its signal peptide, extracellular LRR region and C-terminal hydrophobic anchor fit a cell-surface protein.
Reason: Accept the phylogenetic inference. F4JLB7 sits within the family clade that inherited the term (PANTHER 19.0 places it sister to TMM/RLP29), and its own architecture is that of a secretory-pathway, cell-surface LRR protein. One of the four seeds is AT4G28560 itself. That seed may come from the apical-plasma-membrane IDA from PMID:11752391, which this review removes as a wrong-gene attribution. The node is still well grounded by the CLV2, TMM and PII-2 seeds, so the IBA does not depend on the disputed row.
Supporting Evidence:
file:ARATH/F4JLB7/F4JLB7-uniprot.txt
DR InterPro; IPR001611; Leu-rich_rpt. DR InterPro; IPR032675; LRR_dom_sf. ... FT SIGNAL 1..22 FT /evidence="ECO:0000256|SAM:SignalP" ... GRALYSSARK VLPLIYFPAT LLALYISITQ
In the PANTHER 19.0 tree F4JLB7 is sister to the clade containing TMM (TOO MANY MOUTHS, Q9SSD1) and RLP29 (Q9SJH6), both in subfamily SF42 (node PTN008481374).
Summary: PAINT propagated signaling receptor activity from CLV2 at the PTHR48004 root node. F4JLB7 has the noncatalytic extracellular-LRR receptor-like architecture shared by CLV2 and TMM.
Reason: Accept the curated node placement. The PAINT curator put this broad MF at the family root, not only on the CLV2 clade, and F4JLB7 descends from that node. Nothing specific to the target argues for loss: the LRR solenoid is intact and the protein is anchored at the cell surface. The curator did not propagate CLV2- or TMM-specific terms such as coreceptor activity, CLE or EPF peptide recognition, or stomatal and meristem processes, and this review treats that omission as deliberate. F4JLB7 is in its own subfamily (SF38), not in SF42 with TMM or SF9 with CLV2. The term is kept at this general level, and the ligand and partner kinases are unresolved.
Summary: Membrane localization is correct but general. The UniProt subcellular location behind this mapping is an ARBA prediction ("Single-pass type I membrane protein").
Reason: The term is true but less specific than the evidence allows. The signal peptide, extracellular LRR region, C-terminal hydrophobic anchor and the PAINT IBA all point to the plasma membrane, a term the gene already carries. Refine to plasma membrane. Whether the C-terminal segment is a transmembrane anchor or a GPI-attachment signal is unresolved, so no anchoring-specific term is proposed.
DR InterPro; IPR001611; Leu-rich_rpt. DR InterPro; IPR032675; LRR_dom_sf. ... FT SIGNAL 1..22 FT /evidence="ECO:0000256|SAM:SignalP" ... GRALYSSARK VLPLIYFPAT LLALYISITQ
In the PANTHER 19.0 tree F4JLB7 is sister to the clade containing TMM (TOO MANY MOUTHS, Q9SSD1) and RLP29 (Q9SJH6), both in subfamily SF42 (node PTN008481374).
TAS PMID:12068095 Prediction of glycosylphosphatidylinositol-anchored proteins...
MODIFY
Summary: This TAIR TAS row cites the Borner et al. 2002 genome-wide prediction of GPI-anchored proteins. The authors predicted that such proteins are targeted to the plasma membrane and cell wall.
Reason: Membrane is true but general. The cited study frames GPI anchoring as targeting proteins to the plasma membrane, which matches the PAINT IBA and the target architecture. Only the abstract is cached, so this review cannot confirm whether At4g28560 is in the predicted GPI-anchored set. The localization is supported independently, so refine to plasma membrane.
TAS PMID:12805588 Identification of glycosylphosphatidylinositol-anchored prot...
MODIFY
Summary: This TAIR TAS row cites the Borner et al. 2003 proteomic identification of GPI-anchored proteins. That study recovered four receptor-like proteins from PI-PLC-sensitive fractions.
Reason: Membrane is true but general. The cached abstract does not name the four receptor-like proteins, so whether F4JLB7 was among the proteomically confirmed GPI-anchored proteins is not verified here. The supported specific localization is the plasma membrane, which the gene already carries by IBA.
30 GAPs were identified, including six beta-1,3 glucanases, five phytocyanins, four fasciclin-like arabinogalactan proteins, four receptor-like proteins
file:ARATH/F4JLB7/F4JLB7-uniprot.txt
FT SIGNAL 1..22 FT /evidence="ECO:0000256|SAM:SignalP"
Summary: The chloroplast assignment is a computational AtSubP prediction. It conflicts with the N-terminal signal peptide (residues 1-22), the extracellular-type LRR region, the hydrophobic C terminus and the curated plasma-membrane IBA of the deposited F4JLB7 sequence.
Reason: This is an unreviewed electronic localization prediction, and it is contradicted by the protein's own architecture. An N-terminal signal peptide directs proteins into the secretory pathway, not to plastids, and the LRR receptor-like organization matches the plasma-membrane localization accepted from the PAINT IBA in this review. No experiment places F4JLB7 in chloroplasts. The RIC7 localization literature concerns the adjacent CRIB locus AT4G28556 and cannot be used for this protein in either direction. Removing an electronic prediction that is contradicted on sequence grounds follows the project's guidance for IEA/ISM inferences.
Supporting Evidence:
file:ARATH/F4JLB7/F4JLB7-uniprot.txt
DR InterPro; IPR001611; Leu-rich_rpt. DR InterPro; IPR032675; LRR_dom_sf. ... FT SIGNAL 1..22 FT /evidence="ECO:0000256|SAM:SignalP" ... GRALYSSARK VLPLIYFPAT LLALYISITQ
In the PANTHER 19.0 tree F4JLB7 is sister to the clade containing TMM (TOO MANY MOUTHS, Q9SSD1) and RLP29 (Q9SJH6), both in subfamily SF42 (node PTN008481374).
IPI PMID:11752391 A genome-wide analysis of Arabidopsis Rop-interactive CRIB m...
REMOVE
Summary: The published RIC7 cloning primers in PMID:11752391 match the adjacent AT4G28556 CRIB gene, supporting probable wrong-gene attribution of ROP binding to F4JLB7.
Reason: This experimental row was assigned to the wrong gene product. A reproducible sequence analysis maps all published RIC7 cloning and RT-PCR primers from this study (and two later RIC7 studies) to the adjacent, oppositely oriented locus AT4G28556, which encodes the 216-residue CRIB protein Q1G3K8. None of the primers matches the AT4G28560 transcript that encodes F4JLB7. Both loci carry the TAIR symbol RIC7, which explains the attribution. The paper's ROP-binding assay concerns a CRIB-motif protein, and the CRIB motif is required for binding GTP-bound Rop1. F4JLB7 has no CRIB motif, only LRRs and a signal peptide, so it cannot be the ROP effector assayed. The interaction partner in the GOA row (AT3G51300, ROP1) fits the CRIB protein Q1G3K8. This removal rests on positive sequence evidence about which locus was assayed, not on the abstract's gene focus. The function itself is not disputed and belongs on Q1G3K8.
IMP PMID:11752391 A genome-wide analysis of Arabidopsis Rop-interactive CRIB m...
REMOVE
Summary: The published RIC7 cloning primers in PMID:11752391 match the adjacent AT4G28556 CRIB gene, supporting probable wrong-gene attribution of the pollen-tube overexpression phenotype to F4JLB7.
Reason: This experimental row was assigned to the wrong gene product. A reproducible sequence analysis maps all published RIC7 cloning and RT-PCR primers from this study (and two later RIC7 studies) to the adjacent, oppositely oriented locus AT4G28556, which encodes the 216-residue CRIB protein Q1G3K8. None of the primers matches the AT4G28560 transcript that encodes F4JLB7. Both loci carry the TAIR symbol RIC7, which explains the attribution. The pollen-tube phenotype comes from overexpressing the cloned RIC7 construct in tobacco pollen, and the primers identify that construct as the CRIB locus. This removal rests on positive sequence evidence about which locus was assayed, not on the abstract's gene focus. The function itself is not disputed and belongs on Q1G3K8.
IDA PMID:11752391 A genome-wide analysis of Arabidopsis Rop-interactive CRIB m...
REMOVE
Summary: The published RIC7 cloning primers in PMID:11752391 match the adjacent AT4G28556 CRIB gene, supporting probable wrong-gene attribution of apical plasma-membrane localization to F4JLB7.
Reason: This experimental row was assigned to the wrong gene product. A reproducible sequence analysis maps all published RIC7 cloning and RT-PCR primers from this study (and two later RIC7 studies) to the adjacent, oppositely oriented locus AT4G28556, which encodes the 216-residue CRIB protein Q1G3K8. None of the primers matches the AT4G28560 transcript that encodes F4JLB7. Both loci carry the TAIR symbol RIC7, which explains the attribution. The GFP-RIC7 apical localization was imaged with the construct that the primers identify as the CRIB locus. Plasma-membrane association of F4JLB7 is supported separately by the IBA row, but this experiment is not evidence for it. This removal rests on positive sequence evidence about which locus was assayed, not on the abstract's gene focus. The function itself is not disputed and belongs on Q1G3K8.
IC PMID:11751054 The leucine-rich repeat as a protein recognition motif.
ACCEPT
Summary: TIGR made this IC inference in 2003 from a general LRR review, with GO:0005515 as its basis. Broad participation in signal transduction follows from the signaling receptor activity that PAINT assigns to the family.
Reason: Accept at this broad level. A signaling receptor takes part in signal transduction by definition, and the IBA receptor-activity row supports that for F4JLB7. The IC's GO:0005515 basis cannot carry the inference: the only protein-binding row for this accession is the ROP1 IPI, which is removed here as a wrong-gene attribution. No specific pathway is known for F4JLB7. This row does not support the ROP2-RIC7-Exo70B1 guard-cell pathway, which belongs to the CRIB protein Q1G3K8, or the stomatal ERECTA/TMM pathway of its paralog TMM.
TMM-specific functions (EPF-peptide recognition with ERECTA-family receptors in stomatal patterning) are not transferable to F4JLB7 on this basis.
file:ARATH/F4JLB7/F4JLB7-uniprot.txt
DR InterPro; IPR001611; Leu-rich_rpt. DR InterPro; IPR032675; LRR_dom_sf.
Core Functions
Noncatalytic cell-surface LRR receptor-like protein. It is predicted, from PAINT inference at the PTHR48004 family root and from its signal peptide, extracellular LRR solenoid and C-terminal anchor, to act as a signaling receptor at the plasma membrane. Its ligand, partner receptor kinases and biological process are unknown. It lies in its own subfamily, sister to the TMM/RLP29 clade.
DR InterPro; IPR001611; Leu-rich_rpt. DR InterPro; IPR032675; LRR_dom_sf. ... FT SIGNAL 1..22 FT /evidence="ECO:0000256|SAM:SignalP" ... GRALYSSARK VLPLIYFPAT LLALYISITQ
In the PANTHER 19.0 tree F4JLB7 is sister to the clade containing TMM (TOO MANY MOUTHS, Q9SSD1) and RLP29 (Q9SJH6), both in subfamily SF42 (node PTN008481374).
Q: Published RIC7 primers match AT4G28556/Q1G3K8 rather than AT4G28560/F4JLB7. At which stage of source curation or AGI-to-UniProt export were the three PMID:11752391 experimental annotations associated with F4JLB7, and what source-level correction preserves the original assay provenance?
Suggested experts: TAIR curators
Q: Is the C-terminal hydrophobic segment of F4JLB7 (residues ~431-450, with no cytoplasmic tail) a transmembrane anchor or a GPI-attachment signal? Was At4g28560 among the four receptor-like proteins recovered from PI-PLC-sensitive fractions by Borner et al. (2003)?
Suggested experts: TAIR curators, plant GPI-anchored protein researchers
Q: Should the UniProt SubName "ROP-interactive CRIB motif-containing protein 7" and the RIC7 gene name on F4JLB7 be revised? F4JLB7 has no CRIB motif and the CRIB-motif RIC7 is encoded by At4g28556 (Q1G3K8).
Suggested experts: UniProt curators, TAIR curators
Suggested Experiments
Experiment: Express a fluorescent-protein fusion of F4JLB7 placed after the signal peptide in Arabidopsis. Test plasma-membrane localization, and test release by phosphatidylinositol-specific phospholipase C to distinguish GPI anchoring from a transmembrane anchor.
Type: subcellular localization and PI-PLC sensitivity assay
Experiment: Use co-immunoprecipitation or proximity labelling to look for receptor-kinase partners of F4JLB7. Test LRR-RLKs that partner TMM and CLV2 (ERECTA family, CORYNE/CRN). Phenotype at4g28560 loss-of-function lines for stomatal patterning and meristem traits, where its paralogs act.
Type: protein interaction and genetic analysis
External Prediction Reviews
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
F4JLB7 (At4g28560) is a 450-residue noncatalytic leucine-rich-repeat receptor-like protein with an N-terminal signal peptide, an extracellular LRR solenoid and a C-terminal hydrophobic anchor. In the PANTHER PTHR48004 tree it is sister to the TMM/RLP29 clade, and PAINT assigns the family signaling receptor activity at the plasma membrane. It has no protein kinase domain, so the ProtNLM2 kinase activity prediction is rejected. Participation in phosphorylation through a partner receptor kinase is neither established nor excluded, and no publication reports experiments on this locus.
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: No GOA annotation on F4JLB7 covers phosphorylation, so the prediction would be novel. The protein lacks a protein kinase domain (OpenScientist domain and motif analysis), so it cannot phosphorylate a substrate itself. A noncatalytic LRR receptor-like protein could still take part in phosphorylation-based signaling with a partner receptor kinase, as its sister-clade paralog TMM does with ERECTA-family kinases, but that relative is in a different subfamily and its specific functions are not transferable. The gene review accepts only broad signaling receptor activity and signal transduction, with no known ligand, partner or pathway. A PubMed search for At4g28560 returns no experimental papers. Nothing on the target establishes or excludes a role in phosphorylation, so the prediction remains uncertain.
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
DOMAIN ARCHITECTURE MISMATCH
Review rationale: Kinase activity is refuted by the protein's architecture. The 450-residue sequence carries only LRR signatures (InterPro IPR001611, IPR032675; Pfam LRR_1, LRR_8), a signal peptide and a C-terminal hydrophobic anchor with essentially no cytoplasmic tail, leaving no room for a cytoplasmic kinase domain. The OpenScientist analysis finds no protein-kinase Pfam or InterPro domain and no ordered catalytic motifs; the isolated DFG-like tripeptide lies within the LRR solenoid. This is a computational assessment, not a biochemical assay. The re-reviewed gene review treats F4JLB7 as a noncatalytic cell-surface receptor-like protein, and neither GOA nor the PAINT node for PTHR48004 assigns any kinase activity. The prediction is NPI.
Supporting Evidence:
file:ARATH/F4JLB7/F4JLB7-hypotheses/prediction-kinase-activity/openscientist.md: "Second, a **direct motif scan** of the sequence recovered 9 canonical LRR cores but found no ordered kinase catalytic triad; the isolated "DFG" (position 149, inside PEDFGSV) and a "GNGFHG" hit (position 186) are coincidental tripeptides embedded within the LRR solenoid, not part of a folded catalytic cleft."