| Category | Findings for RIC7 (Arabidopsis thaliana) | Evidence / citation |
|---|---|---|
| Gene / protein identity | **RIC7**; Arabidopsis locus **At4g28560**; UniProt accession **F4JLB7**; protein name **ROP-interactive CRIB motif-containing protein 7**; organism **Arabidopsis thaliana**. Identity is consistent with the Arabidopsis RIC family described as CRIB-domain ROP effectors. | (pqac-00000000, pqac-00000008) |
| Family / defining features | RIC7 belongs to the **RIC (ROP-interactive CRIB motif-containing)** family, a set of structurally divergent Arabidopsis ROP effectors that bind activated ROP GTPases via a **CRIB domain**. Arabidopsis contains **11 RIC proteins**. | (pqac-00000000, pqac-00000007, pqac-00000011) |
| Current domain understanding | The defining experimentally supported feature is the **CRIB motif/domain**, which mediates interaction with active ROPs in plant RIC proteins. More broadly, CRIB-containing proteins function as downstream effectors of Rho/ROP-family GTPases. | (pqac-00000000, pqac-00000007, pqac-00000011) |
| Primary molecular function | RIC7 is a **negative regulator of stomatal movement**, especially **light-induced stomatal opening**; it also suppresses **ABA-induced stomatal closure**. Mechanistically, it acts **downstream of ROP2** and inhibits the positive stomatal-opening factor **Exo70B1**, thereby restraining excess opening. | (pqac-00000000, pqac-00000002, pqac-00000012, pqac-00000013) |
| Pathway position | In the best-supported pathway, **active ROP2 → RIC7 → Exo70B1 inhibition**, with RIC7 functioning as a **linker/effector** that transduces ROP2 signaling to vesicle-trafficking machinery in guard cells. | (pqac-00000012, pqac-00000013) |
| Direct interaction partners | **ROP2**: prior work placed RIC7 downstream of active ROP2; **Exo70B1**: directly binds RIC7 in yeast two-hybrid, in vitro pull-down, and BiFC assays. Exo70B1 did **not** bind ROP2 directly in the reported BiFC assay, supporting a linker role for RIC7. | (pqac-00000000, pqac-00000004, pqac-00000012) |
| Positive / opposing functional partner | **Exo70B1** is a **positive regulator** of light-induced stomatal opening, whereas **RIC7 is negative**; the exo70b1 phenotype is epistatic to ric7 in double mutants, supporting Exo70B1 as a downstream target of RIC7. | (pqac-00000005, pqac-00000003, pqac-00000013) |
| Subcellular localization | In guard cells under **dark** conditions, RIC7 is localized **mostly to the nucleus**; under **light** or with **constitutively active ROP2**, a subset of RIC7 relocates to the **plasma membrane region**, where it co-localizes with Exo70B1. This dynamic relocalization is consistent with stimulus-dependent signaling. | (pqac-00000003, pqac-00000005) |
| Localization context of partner | Exo70B1 localizes to the **plasma membrane region**, **nucleus**, and **cytosolic puncta**; it co-localizes with **Exo84B** but shows little co-localization with **Golgi** or **TGN/EE** markers, suggesting association with exocyst-related / noncanonical trafficking compartments relevant to RIC7 action. | (pqac-00000003, pqac-00000012, pqac-00000013) |
| Tissue / expression context | RIC7 promoter activity is detected broadly in young tissues and is **high in stomatal guard cells**, supporting a direct role in guard-cell physiology. | (pqac-00000002) |
| Biological processes implicated | **Guard-cell signaling**, **stomatal opening**, **ABA-responsive stomatal closure**, and likely **vesicle trafficking / membrane remodeling** needed for stomatal movement. The proposed mechanism is inhibition of exocyst-mediated trafficking required for rapid opening. | (pqac-00000000, pqac-00000013) |
| Functional model | Light activates stomatal opening pathways but also a brake mechanism: **ROP2 recruits RIC7 and Exo70B1 to the plasma membrane region; RIC7 binds Exo70B1 and inhibits its function**, fine-tuning opening kinetics and preventing excessive water loss. | (pqac-00000003, pqac-00000012, pqac-00000013) |
| Genetic evidence | **ric7-1 knockout** shows **faster light-induced opening** and **faster ABA-induced closure** than wild type; **RIC7 complementation** restores wild-type behavior; **RIC7 overexpression** slows both responses. | (pqac-00000002) |
| Biochemical / cell-biological evidence | Evidence includes **yeast two-hybrid**, **in vitro GST pull-down**, **BiFC**, **transient fluorescent localization in Vicia faba guard cells**, and **Arabidopsis mutant / complementation / overexpression analysis**. Together these support direct RIC7–Exo70B1 interaction and dynamic localization. | (pqac-00000004, pqac-00000005, pqac-00000003) |
| Broader family context | RIC proteins are diverse ROP effectors. Other Arabidopsis RICs regulate **actin and microtubule organization** and polarized growth, indicating that RIC7 likely represents a specialized branch of ROP effector biology tied to guard-cell membrane trafficking rather than the canonical pollen-tube cytoskeletal outputs of RIC1/3/4. | (pqac-00000000, pqac-00000008, pqac-00000011) |
| Key references summarized in evidence base | Primary experimental study: **Hong et al., 2016, New Phytologist** on the **ROP2–RIC7–Exo70B1** pathway in stomatal opening. Conceptual background from ROP signaling reviews in **Plant Physiology 2018** and **Plant Physiology 2021**. | (pqac-00000000, pqac-00000008, pqac-00000011) |


*Table: This table compiles the verified identity, molecular function, localization, pathway role, and supporting evidence for Arabidopsis RIC7. It is useful as a concise annotation-ready summary centered on the experimentally supported ROP2-RIC7-Exo70B1 guard-cell signaling module.*