RIC7

UniProt ID: Q1G3K8
Organism: Arabidopsis thaliana
Review Status: COMPLETE
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Gene Description

RIC7 is a CRIB-domain effector of plant ROP small GTPases. It binds activated ROP1 and ROP2 and is recruited to the plasma membrane during signaling. In guard cells it restrains light-induced stomatal opening through a pathway involving the exocyst component Exo70B1. RIC7 also attenuates ABA-induced stomatal closure, with elevated RIC7 expression associated with reduced guard-cell ROS accumulation. The protein occupies nuclear, cytoplasmic and peripheral plasma-membrane pools, with its distribution depending on light and ROP activation. RIC7 also interacts with ROP1 in pollen-tube signaling; heterologous overexpression reduces pollen-tube elongation.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0003674 molecular_function
ND
GO_REF:0000015 		MODIFY
Summary: RIC7 binds activated ROP small GTPases; its molecular function is experimentally characterized.
Reason: The ND root annotation does not capture the ROP-effector activity. Prefer small GTPase binding (GO:0031267): Jeon et al. demonstrate preferential binding to GTP-loaded ROP2 in Figure 7D (PMID:18178769), and Wu et al. report ROP1 interaction (PMID:11752391).
Proposed replacements: small GTPase binding
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Interacts with ARAC4/ROP2 and ARAC11/ROP1.
GO:0005634 nucleus
IDA
PMID:18178769
The Arabidopsis small G protein ROP2 is activated by light i... 		KEEP AS NON CORE
Summary: RIC7 accumulates in guard-cell nuclei in darkness.
Reason: GFP-RIC7 imaging supports nuclear localization under dark or inactive-ROP2 conditions (PMID:18178769, Figure 7). Retain this conditional location; a specific nuclear activity has not been established.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
In guard cells in the CC dark localizes predominantly in the nucleus
GO:0005634 nucleus
IEA
GO_REF:0000044 		KEEP AS NON CORE
Summary: The nuclear-location mapping agrees with experimentally observed dark-state localization.
Reason: The Swiss-Prot location maps to a real RIC7 pool documented in PMID:18178769. It does not imply a constitutive nuclear role or transcriptional activity.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
In guard cells in the CC dark localizes predominantly in the nucleus
GO:0005634 nucleus
ISM
GO_REF:0000122 		KEEP AS NON CORE
Summary: The nuclear prediction is consistent with the observed nuclear pool of RIC7.
Reason: Nuclear localization is independently supported by GFP-RIC7 imaging in PMID:18178769. The AtSubP prediction is compatible with that conditional distribution, although it cannot describe light-dependent redistribution.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
In guard cells in the CC dark localizes predominantly in the nucleus
GO:0005737 cytoplasm
EXP
PMID:11752391
A genome-wide analysis of Arabidopsis Rop-interactive CRIB m... 		ACCEPT
Summary: RIC7 has a cytoplasmic pool in pollen tubes.
Reason: The RIC7 localization experiments in PMID:11752391 support a soluble intracellular pool alongside membrane-associated protein. This distribution is compatible with recruitment of a CRIB-containing ROP effector.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cytoplasm CC {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769}.
GO:0005737 cytoplasm
EXP
PMID:18178769
The Arabidopsis small G protein ROP2 is activated by light i... 		ACCEPT
Summary: RIC7 occurs in the guard-cell cytoplasm following illumination.
Reason: The cytoplasmic pool accompanies light-dependent redistribution in the ROP2 experiments (PMID:18178769); it is consistent with a soluble effector that can be recruited to the plasma membrane.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cytoplasm CC {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769}.
GO:0005737 cytoplasm
IEA
GO_REF:0000044 		ACCEPT
Summary: The cytoplasm mapping reflects an experimentally supported RIC7 location.
Reason: Swiss-Prot curates cytoplasmic localization from PMID:11752391 and PMID:18178769. This is consistent with the protein's dynamic intracellular distribution.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cytoplasm CC {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769}.
GO:0005886 plasma membrane
EXP
PMID:11752391
A genome-wide analysis of Arabidopsis Rop-interactive CRIB m... 		ACCEPT
Summary: RIC7 associates with the pollen-tube plasma membrane.
Reason: The localization experiments in PMID:11752391 support membrane recruitment of RIC7 during ROP signaling. Membrane association is peripheral rather than evidence for an integral membrane receptor.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cell CC membrane {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769};
GO:0005886 plasma membrane
IBA
GO_REF:0000033 		ACCEPT
Summary: Plasma-membrane association is consistent with the inherited RIC-family effector role.
Reason: The PAINT inference at PANTHER:PTN005297055 agrees with target-specific localization in PMID:11752391 and PMID:18178769. There is no target-specific evidence against inheritance of this location.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cell CC membrane {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769};
GO:0005886 plasma membrane
IDA
PMID:18178769
The Arabidopsis small G protein ROP2 is activated by light i... 		ACCEPT
Summary: Activated ROP2 recruits RIC7 to the guard-cell plasma membrane.
Reason: Figure 7 of PMID:18178769 directly documents membrane recruitment following illumination or expression of constitutively active ROP2. This location is central to RIC7 signaling.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cell CC membrane {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769};
GO:0005886 plasma membrane
IEA
GO_REF:0000120 		ACCEPT
Summary: The electronic plasma-membrane annotation agrees with experimental localization.
Reason: The target-specific experiments in PMID:11752391 and PMID:18178769 demonstrate plasma-membrane association and support this electronic annotation.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Cell CC membrane {ECO:0000269|PubMed:11752391, ECO:0000269|PubMed:18178769};
GO:0009416 response to light stimulus
IDA
PMID:18178769
The Arabidopsis small G protein ROP2 is activated by light i... 		KEEP AS NON CORE
Summary: RIC7 participates in the guard-cell response to light.
Reason: The RIC7 experiments in PMID:18178769 show light-dependent redistribution and inhibition of light-induced stomatal opening. Retain this broad response as non-core; negative regulation of stomatal opening describes the physiological role more precisely. Redistribution supports responsiveness to light without establishing direct photoreception.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
involved in the prevention of excessive stomatal opening upon light CC stimulation.
GO:0009860 pollen tube growth
IBA
GO_REF:0000033 		KEEP AS NON CORE
Summary: RIC7 participates in ROP-dependent pollen-tube growth regulation.
Reason: The PAINT inference at PANTHER:PTN008200783 is consistent with ROP1 binding, pollen expression and the heterologous overexpression phenotype in PMID:11752391. Retain the process without assigning an endogenous inhibitory mechanism from overexpression alone; stomatal regulation has stronger target-specific genetic support.
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Over-expression of RIC7 in tobacco germinating pollen CC reduces pollen tube elongation.
GO:0009966 regulation of signal transduction
IBA
GO_REF:0000033 		ACCEPT
Summary: RIC7 mediates downstream ROP signaling.
Reason: The inference at PANTHER:PTN008706952 is consistent with the experimentally characterized ROP-effector role. RIC7 binds ROP1/ROP2 and links activated ROP2 to control of stomatal movement (PMID:11752391; PMID:18178769; PMID:26451971).
Supporting Evidence:
file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
Functions as a downstream effector of Rho-related GTP binding CC proteins of the 'Rho of Plants' (ROPs) family.
GO:1902457 negative regulation of stomatal opening
IMP
PMID:26451971
The ROP2-RIC7 pathway negatively regulates light-induced sto... 		NEW
Summary: RIC7 restrains light-induced stomatal opening.
Reason: Arabidopsis ric7 loss-of-function, native-promoter complementation and overexpression establish a negative effect on stomatal opening (PMID:26451971). This captures the direction of the genetically demonstrated response.
Supporting Evidence:
PMID:26451971
Light-induced stomatal opening was promoted by ric7 knockout, whereas it was inhibited by RIC7 overexpression
GO:0090333 regulation of stomatal closure
IMP
PMID:33586611
RIC7 plays a negative role in ABA-induced stomatal closure b... 		NEW
Summary: Elevated RIC7 expression attenuates ABA-induced stomatal closure.
Reason: The ric7-2 and ric7-3 promoter-insertion lines increase RIC7 expression and show reduced ABA-induced closure (PMID:33586611), consistent with the independent genetic evidence in PMID:26451971. The effect is negative; the available regulation term captures participation without treating these lines as knockouts or assigning a direct ROS-generating activity.
Supporting Evidence:
PMID:33586611
using two RIC7 overexpressing mutants, we confirmed the negative role of RIC7 in ABA-induced stomatal closure

Core Functions

Binds activated ROP small GTPases to regulate guard-cell movements, restraining light-induced stomatal opening through Exo70B1 and attenuating ABA-induced stomatal closure.

Molecular Function:
small GTPase binding
Directly Involved In:
negative regulation of stomatal opening regulation of stomatal closure
Cellular Locations:
plasma membrane cytoplasm
Supporting Evidence:
  • file:ARATH/Q1G3K8/Q1G3K8-uniprot.txt
    Interacts with ARAC4/ROP2 and ARAC11/ROP1.
  • PMID:26451971
    Light-induced stomatal opening was promoted by ric7 knockout, whereas it was inhibited by RIC7 overexpression
  • PMID:33586611
    using two RIC7 overexpressing mutants, we confirmed the negative role of RIC7 in ABA-induced stomatal closure

References

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Suggested Questions for Experts

Q: Does the nuclear pool of RIC7 have a biochemical function, or serve primarily as a regulated reservoir for membrane recruitment?

Q: What endogenous pollen-tube phenotype follows specific loss of AT4G28556, and how does it relate to the heterologous overexpression phenotype?

Suggested Experiments

Experiment: Introduce a functional fluorescent tag at the endogenous AT4G28556 locus and measure localization and Exo70B1 association during light transitions, using stomatal-aperture rescue to verify tag functionality.

Hypothesis: ROP-dependent redistribution of endogenous RIC7 controls its access to Exo70B1.

Type: Endogenous tagging, live-cell imaging and functional complementation

Experiment: Measure pollen germination, tube elongation and fertility in an AT4G28556-specific loss-of-function line and native-promoter rescue, verifying that adjacent AT4G28560 expression is preserved.

Hypothesis: AT4G28556 contributes to pollen-tube growth at physiological expression levels.

Type: Targeted genetics and pollen phenotyping

Deep Research

Falcon

(Q1G3K8-deep-research-falcon.md)

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📚 Additional Documentation

Notes

(Q1G3K8-notes.md)

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Bioinformatics Results

(RESULTS.md)

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